Reception of random access response

ABSTRACT

In some embodiments, a wireless device transmits a first preamble via a cell. The wireless device receives a downlink grant for a random access response. The wireless device determines a failure to receive the random access response. Based on the failure and a time alignment timer of the cell, the wireless device determines an uplink signal, for transmission via the cell, as one of a second preamble and a negative acknowledgement. The wireless device transmits the uplink signal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/US2020/046,690, filed Aug. 17, 2020, which claims the benefit ofU.S. Provisional Application No. 62/887,279, filed Aug. 15, 2019, eachof which is hereby incorporated by reference in its entirety.

BRIEF DESCRIPTION OF THE DRAWINGS

Examples of several of the various embodiments of the present disclosureare described herein with reference to the drawings.

FIG. 1A and FIG. 1B illustrate example mobile communication networks inwhich embodiments of the present disclosure may be implemented.

FIG. 2A and FIG. 2B respectively illustrate a New Radio (NR) user planeand control plane protocol stack.

FIG. 3 illustrates an example of services provided between protocollayers of the NR user plane protocol stack of FIG. 2A.

FIG. 4A illustrates an example downlink data flow through the NR userplane protocol stack of FIG. 2A.

FIG. 4B illustrates an example format of a MAC subheader in a MAC PDU.

FIG. 5A and FIG. 5B respectively illustrate a mapping between logicalchannels, transport channels, and physical channels for the downlink anduplink.

FIG. 6 is an example diagram showing RRC state transitions of a UE.

FIG. 7 illustrates an example configuration of an NR frame into whichOFDM symbols are grouped.

FIG. 8 illustrates an example configuration of a slot in the time andfrequency domain for an NR carrier.

FIG. 9 illustrates an example of bandwidth adaptation using threeconfigured BWPs for an NR carrier.

FIG. 10A illustrates three carrier aggregation configurations with twocomponent carriers.

FIG. 10B illustrates an example of how aggregated cells may beconfigured into one or more PUCCH groups.

FIG. 11A illustrates an example of an SS/PBCH block structure andlocation.

FIG. 11B illustrates an example of CSI-RSs that are mapped in the timeand frequency domains.

FIG. 12A and FIG. 12B respectively illustrate examples of three downlinkand uplink beam management procedures.

FIG. 13A, FIG. 13B, and FIG. 13C respectively illustrate a four-stepcontention-based random access procedure, a two-step contention-freerandom access procedure, and another two-step random access procedure.

FIG. 14A illustrates an example of CORESET configurations for abandwidth part.

FIG. 14B illustrates an example of a CCE-to-REG mapping for DCItransmission on a CORESET and PDCCH processing.

FIG. 15 illustrates an example of a wireless device in communicationwith a base station.

FIG. 16A, FIG. 16B, FIG. 16C, and FIG. 16D illustrate example structuresfor uplink and downlink transmission.

FIG. 17A is an example of a PRACH occasion TDMed with a UL radioresources as per an aspect of an example embodiment of the presentdisclosure.

FIG. 17B is an example of a PRACH occasion FDMed with a UL radioresources as per an aspect of an example embodiment of the presentdisclosure.

FIG. 17C is an example of a PRACH occasion TDMed and FDMed with a ULradio resources as per an aspect of an example embodiment of the presentdisclosure.

FIG. 18 shows an example of ra-ssb-OccasionMaskIndex values as per anaspect of an example embodiment of the present disclosure.

FIG. 19A is an example of an RAR as per an aspect of an exampleembodiment of the present disclosure.

FIG. 19B is an example of an RAR as per an aspect of an exampleembodiment of the present disclosure.

FIG. 19C is an example of an RAR as per an aspect of an exampleembodiment of the present disclosure.

FIG. 20 is an example of MAC RAR format as per an aspect of an exampleembodiment of the present disclosure.

FIG. 21 is an example RAR format as per an aspect of an exampleembodiment of the present disclosure.

FIG. 22A is an example RAR format as per an aspect of an exampleembodiment of the present disclosure.

FIG. 22B is an example RAR format as per an aspect of an exampleembodiment of the present disclosure.

FIG. 23 is an example diagram showing a two-step RA procedure as per anaspect of an example embodiment of the present disclosure.

FIG. 24 is an example diagram illustrating a two-step RA procedure asper an aspect of an example embodiment of the present disclosure.

FIG. 25A is example diagram of a two-step RA procedure as per an aspectof an example embodiment of the present disclosure.

FIG. 25B is example diagram of a two-step RA procedure as per an aspectof an example embodiment of the present disclosure.

FIG. 26 is an example diagram of an RA procedure as per an aspect of anexample embodiment of the present disclosure.

FIG. 27A is an example diagram of receiving one or more PDSCHs as per anaspect of an example embodiment of the present disclosure.

FIG. 27B is an example diagram of receiving one or more PDSCHs as per anaspect of an example embodiment of the present disclosure.

FIG. 28A is an example diagram of transmitting one or more PDSCH as peran aspect of an example embodiment of the present disclosure.

FIG. 28B is an example diagram of transmitting one or more PDSCH as peran aspect of an example embodiment of the present disclosure.

FIG. 29 is an example of adjusted window as per an aspect of an exampleembodiment of the present disclosure.

FIG. 30 shows an example of adjusted window as per an aspect of anexample embodiment of the present disclosure.

FIG. 31 is an example diagram of PUCCH and/or MsgA transmission as peran aspect of an example embodiment of the present disclosure.

FIG. 32 is a flow diagram of a wireless device as per an aspect of anexample embodiment of the present disclosure.

FIG. 33 is a flow diagram of a base station as per an aspect of anexample embodiment of the present disclosure.

DETAILED DESCRIPTION

In the present disclosure, various embodiments are presented as examplesof how the disclosed techniques may be implemented and/or how thedisclosed techniques may be practiced in environments and scenarios. Itwill be apparent to persons skilled in the relevant art that variouschanges in form and detail can be made therein without departing fromthe scope. In fact, after reading the description, it will be apparentto one skilled in the relevant art how to implement alternativeembodiments. The present embodiments should not be limited by any of thedescribed exemplary embodiments. The embodiments of the presentdisclosure will be described with reference to the accompanyingdrawings. Limitations, features, and/or elements from the disclosedexample embodiments may be combined to create further embodiments withinthe scope of the disclosure. Any figures which highlight thefunctionality and advantages, are presented for example purposes only.The disclosed architecture is sufficiently flexible and configurable,such that it may be utilized in ways other than that shown. For example,the actions listed in any flowchart may be re-ordered or only optionallyused in some embodiments.

Embodiments may be configured to operate as needed. The disclosedmechanism may be performed when certain criteria are met, for example,in a wireless device, a base station, a radio environment, a network, acombination of the above, and/or the like. Example criteria may bebased, at least in part, on for example, wireless device or network nodeconfigurations, traffic load, initial system set up, packet sizes,traffic characteristics, a combination of the above, and/or the like.When the one or more criteria are met, various example embodiments maybe applied. Therefore, it may be possible to implement exampleembodiments that selectively implement disclosed protocols.

A base station may communicate with a mix of wireless devices. Wirelessdevices and/or base stations may support multiple technologies, and/ormultiple releases of the same technology. Wireless devices may have somespecific capability(ies) depending on wireless device category and/orcapability(ies). When this disclosure refers to a base stationcommunicating with a plurality of wireless devices, this disclosure mayrefer to a subset of the total wireless devices in a coverage area. Thisdisclosure may refer to, for example, a plurality of wireless devices ofa given LTE or 5G release with a given capability and in a given sectorof the base station. The plurality of wireless devices in thisdisclosure may refer to a selected plurality of wireless devices, and/ora subset of total wireless devices in a coverage area which performaccording to disclosed methods, and/or the like. There may be aplurality of base stations or a plurality of wireless devices in acoverage area that may not comply with the disclosed methods, forexample, those wireless devices or base stations may perform based onolder releases of LTE or 5G technology.

In this disclosure, “a” and “an” and similar phrases are to beinterpreted as “at least one” and “one or more.” Similarly, any termthat ends with the suffix “(s)” is to be interpreted as “at least one”and “one or more.” In this disclosure, the term “may” is to beinterpreted as “may, for example.” In other words, the term “may” isindicative that the phrase following the term “may” is an example of oneof a multitude of suitable possibilities that may, or may not, beemployed by one or more of the various embodiments. The terms“comprises” and “consists of”, as used herein, enumerate one or morecomponents of the element being described. The term “comprises” isinterchangeable with “includes” and does not exclude unenumeratedcomponents from being included in the element being described. Bycontrast, “consists of” provides a complete enumeration of the one ormore components of the element being described. The term “based on”, asused herein, should be interpreted as “based at least in part on” ratherthan, for example, “based solely on”. The term “and/or” as used hereinrepresents any possible combination of enumerated elements. For example,“A, B, and/or C” may represent A; B; C; A and B; A and C; B and C; or A,B, and C.

If A and B are sets and every element of A is an element of B, A iscalled a subset of B. In this specification, only non-empty sets andsubsets are considered. For example, possible subsets of B={cell1,cell2} are: {cell1}, {cell2}, and {cell1, cell2}. The phrase “based on”(or equally “based at least on”) is indicative that the phrase followingthe term “based on” is an example of one of a multitude of suitablepossibilities that may, or may not, be employed to one or more of thevarious embodiments. The phrase “in response to” (or equally “inresponse at least to”) is indicative that the phrase following thephrase “in response to” is an example of one of a multitude of suitablepossibilities that may, or may not, be employed to one or more of thevarious embodiments. The phrase “depending on” (or equally “depending atleast to”) is indicative that the phrase following the phrase “dependingon” is an example of one of a multitude of suitable possibilities thatmay, or may not, be employed to one or more of the various embodiments.The phrase “employing/using” (or equally “employing/using at least”) isindicative that the phrase following the phrase “employing/using” is anexample of one of a multitude of suitable possibilities that may, or maynot, be employed to one or more of the various embodiments.

The term configured may relate to the capacity of a device whether thedevice is in an operational or non-operational state. Configured mayrefer to specific settings in a device that effect the operationalcharacteristics of the device whether the device is in an operational ornon-operational state. In other words, the hardware, software, firmware,registers, memory values, and/or the like may be “configured” within adevice, whether the device is in an operational or nonoperational state,to provide the device with specific characteristics. Terms such as “acontrol message to cause in a device” may mean that a control messagehas parameters that may be used to configure specific characteristics ormay be used to implement certain actions in the device, whether thedevice is in an operational or non-operational state.

In this disclosure, parameters (or equally called, fields, orInformation elements: IEs) may comprise one or more information objects,and an information object may comprise one or more other objects. Forexample, if parameter (IE) N comprises parameter (IE) M, and parameter(IE) M comprises parameter (IE) K, and parameter (IE) K comprisesparameter (information element) J. Then, for example, N comprises K, andN comprises J. In an example embodiment, when one or more messagescomprise a plurality of parameters, it implies that a parameter in theplurality of parameters is in at least one of the one or more messages,but does not have to be in each of the one or more messages.

Many features presented are described as being optional through the useof “may” or the use of parentheses. For the sake of brevity andlegibility, the present disclosure does not explicitly recite each andevery permutation that may be obtained by choosing from the set ofoptional features. The present disclosure is to be interpreted asexplicitly disclosing all such permutations. For example, a systemdescribed as having three optional features may be embodied in sevenways, namely with just one of the three possible features, with any twoof the three possible features or with three of the three possiblefeatures.

Many of the elements described in the disclosed embodiments may beimplemented as modules. A module is defined here as an element thatperforms a defined function and has a defined interface to otherelements. The modules described in this disclosure may be implemented inhardware, software in combination with hardware, firmware, wetware (e.g.hardware with a biological element) or a combination thereof, which maybe behaviorally equivalent. For example, modules may be implemented as asoftware routine written in a computer language configured to beexecuted by a hardware machine (such as C, C++, Fortran, Java, Basic,Matlab or the like) or a modeling/simulation program such as Simulink,Stateflow, GNU Octave, or LabVIEWMathScript. It may be possible toimplement modules using physical hardware that incorporates discrete orprogrammable analog, digital and/or quantum hardware. Examples ofprogrammable hardware comprise: computers, microcontrollers,microprocessors, application-specific integrated circuits (ASICs); fieldprogrammable gate arrays (FPGAs); and complex programmable logic devices(CPLDs). Computers, microcontrollers and microprocessors are programmedusing languages such as assembly, C, C++ or the like. FPGAs, ASICs andCPLDs are often programmed using hardware description languages (HDL)such as VHSIC hardware description language (VHDL) or Verilog thatconfigure connections between internal hardware modules with lesserfunctionality on a programmable device. The mentioned technologies areoften used in combination to achieve the result of a functional module.

FIG. 1A illustrates an example of a mobile communication network 100 inwhich embodiments of the present disclosure may be implemented. Themobile communication network 100 may be, for example, a public landmobile network (PLMN) run by a network operator. As illustrated in FIG.1A, the mobile communication network 100 includes a core network (CN)102, a radio access network (RAN) 104, and a wireless device 106.

The CN 102 may provide the wireless device 106 with an interface to oneor more data networks (DNs), such as public DNs (e.g., the Internet),private DNs, and/or intra-operator DNs. As part of the interfacefunctionality, the CN 102 may set up end-to-end connections between thewireless device 106 and the one or more DNs, authenticate the wirelessdevice 106, and provide charging functionality.

The RAN 104 may connect the CN 102 to the wireless device 106 throughradio communications over an air interface. As part of the radiocommunications, the RAN 104 may provide scheduling, radio resourcemanagement, and retransmission protocols. The communication directionfrom the RAN 104 to the wireless device 106 over the air interface isknown as the downlink and the communication direction from the wirelessdevice 106 to the RAN 104 over the air interface is known as the uplink.Downlink transmissions may be separated from uplink transmissions usingfrequency division duplexing (FDD), time-division duplexing (TDD),and/or some combination of the two duplexing techniques.

The term wireless device may be used throughout this disclosure to referto and encompass any mobile device or fixed (non-mobile) device forwhich wireless communication is needed or usable. For example, awireless device may be a telephone, smart phone, tablet, computer,laptop, sensor, meter, wearable device, Internet of Things (IoT) device,vehicle road side unit (RSU), relay node, automobile, and/or anycombination thereof. The term wireless device encompasses otherterminology, including user equipment (UE), user terminal (UT), accessterminal (AT), mobile station, handset, wireless transmit and receiveunit (WTRU), and/or wireless communication device.

The RAN 104 may include one or more base stations (not shown). The termbase station may be used throughout this disclosure to refer to andencompass a Node B (associated with UMTS and/or 3G standards), anEvolved Node B (eNB, associated with E-UTRA and/or 4G standards), aremote radio head (RRH), a baseband processing unit coupled to one ormore RRHs, a repeater node or relay node used to extend the coveragearea of a donor node, a Next Generation Evolved Node B (ng-eNB), aGeneration Node B (gNB, associated with NR and/or 5G standards), anaccess point (AP, associated with, for example, WiFi or any othersuitable wireless communication standard), and/or any combinationthereof. A base station may comprise at least one gNB Central Unit(gNB-CU) and at least one a gNB Distributed Unit (gNB-DU).

A base station included in the RAN 104 may include one or more sets ofantennas for communicating with the wireless device 106 over the airinterface. For example, one or more of the base stations may includethree sets of antennas to respectively control three cells (or sectors).The size of a cell may be determined by a range at which a receiver(e.g., a base station receiver) can successfully receive thetransmissions from a transmitter (e.g., a wireless device transmitter)operating in the cell. Together, the cells of the base stations mayprovide radio coverage to the wireless device 106 over a wide geographicarea to support wireless device mobility.

In addition to three-sector sites, other implementations of basestations are possible. For example, one or more of the base stations inthe RAN 104 may be implemented as a sectored site with more or less thanthree sectors. One or more of the base stations in the RAN 104 may beimplemented as an access point, as a baseband processing unit coupled toseveral remote radio heads (RRHs), and/or as a repeater or relay nodeused to extend the coverage area of a donor node. A baseband processingunit coupled to RRHs may be part of a centralized or cloud RANarchitecture, where the baseband processing unit may be eithercentralized in a pool of baseband processing units or virtualized. Arepeater node may amplify and rebroadcast a radio signal received from adonor node. A relay node may perform the same/similar functions as arepeater node but may decode the radio signal received from the donornode to remove noise before amplifying and rebroadcasting the radiosignal.

The RAN 104 may be deployed as a homogenous network of macrocell basestations that have similar antenna patterns and similar high-leveltransmit powers. The RAN 104 may be deployed as a heterogeneous network.In heterogeneous networks, small cell base stations may be used toprovide small coverage areas, for example, coverage areas that overlapwith the comparatively larger coverage areas provided by macrocell basestations. The small coverage areas may be provided in areas with highdata traffic (or so-called “hotspots”) or in areas with weak macrocellcoverage. Examples of small cell base stations include, in order ofdecreasing coverage area, microcell base stations, picocell basestations, and femtocell base stations or home base stations.

The Third-Generation Partnership Project (3GPP) was formed in 1998 toprovide global standardization of specifications for mobilecommunication networks similar to the mobile communication network 100in FIG. 1A. To date, 3GPP has produced specifications for threegenerations of mobile networks: a third generation (3G) network known asUniversal Mobile Telecommunications System (UMTS), a fourth generation(4G) network known as Long-Term Evolution (LTE), and a fifth generation(5G) network known as 5G System (5GS). Embodiments of the presentdisclosure are described with reference to the RAN of a 3GPP 5G network,referred to as next-generation RAN (NG-RAN). Embodiments may beapplicable to RANs of other mobile communication networks, such as theRAN 104 in FIG. 1A, the RANs of earlier 3G and 4G networks, and those offuture networks yet to be specified (e.g., a 3GPP 6G network). NG-RANimplements 5G radio access technology known as New Radio (NR) and may beprovisioned to implement 4G radio access technology or other radioaccess technologies, including non-3GPP radio access technologies.

FIG. 1B illustrates another example mobile communication network 150 inwhich embodiments of the present disclosure may be implemented. Mobilecommunication network 150 may be, for example, a PLMN run by a networkoperator. As illustrated in FIG. 1B, mobile communication network 150includes a 5G core network (5G-CN) 152, an NG-RAN 154, and UEs 156A and156B (collectively UEs 156). These components may be implemented andoperate in the same or similar manner as corresponding componentsdescribed with respect to FIG. 1A.

The 5G-CN 152 provides the UEs 156 with an interface to one or more DNs,such as public DNs (e.g., the Internet), private DNs, and/orintra-operator DNs. As part of the interface functionality, the 5G-CN152 may set up end-to-end connections between the UEs 156 and the one ormore DNs, authenticate the UEs 156, and provide charging functionality.Compared to the CN of a 3GPP 4G network, the basis of the 5G-CN 152 maybe a service-based architecture. This means that the architecture of thenodes making up the 5G-CN 152 may be defined as network functions thatoffer services via interfaces to other network functions. The networkfunctions of the 5G-CN 152 may be implemented in several ways, includingas network elements on dedicated or shared hardware, as softwareinstances running on dedicated or shared hardware, or as virtualizedfunctions instantiated on a platform (e.g., a cloud-based platform).

As illustrated in FIG. 1B, the 5G-CN 152 includes an Access and MobilityManagement Function (AMF) 158A and a User Plane Function (UPF) 158B,which are shown as one component AMF/UPF 158 in FIG. 1B for ease ofillustration. The UPF 158B may serve as a gateway between the NG-RAN 154and the one or more DNs. The UPF 158B may perform functions such aspacket routing and forwarding, packet inspection and user plane policyrule enforcement, traffic usage reporting, uplink classification tosupport routing of traffic flows to the one or more DNs, quality ofservice (QoS) handling for the user plane (e.g., packet filtering,gating, uplink/downlink rate enforcement, and uplink trafficverification), downlink packet buffering, and downlink data notificationtriggering. The UPF 158B may serve as an anchor point forintra-/inter-Radio Access Technology (RAT) mobility, an externalprotocol (or packet) data unit (PDU) session point of interconnect tothe one or more DNs, and/or a branching point to support a multi-homedPDU session. The UEs 156 may be configured to receive services through aPDU session, which is a logical connection between a UE and a DN.

The AMF 158A may perform functions such as Non-Access Stratum (NAS)signaling termination, NAS signaling security, Access Stratum (AS)security control, inter-CN node signaling for mobility between 3GPPaccess networks, idle mode UE reachability (e.g., control and executionof paging retransmission), registration area management, intra-systemand inter-system mobility support, access authentication, accessauthorization including checking of roaming rights, mobility managementcontrol (subscription and policies), network slicing support, and/orsession management function (SMF) selection. NAS may refer to thefunctionality operating between a CN and a UE, and AS may refer to thefunctionality operating between the UE and a RAN.

The 5G-CN 152 may include one or more additional network functions thatare not shown in FIG. 1B for the sake of clarity. For example, the 5G-CN152 may include one or more of a Session Management Function (SMF), anNR Repository Function (NRF), a Policy Control Function (PCF), a NetworkExposure Function (NEF), a Unified Data Management (UDM), an ApplicationFunction (AF), and/or an Authentication Server Function (AUSF).

The NG-RAN 154 may connect the 5G-CN 152 to the UEs 156 through radiocommunications over the air interface. The NG-RAN 154 may include one ormore gNBs, illustrated as gNB 160A and gNB 160B (collectively gNBs 160)and/or one or more ng-eNBs, illustrated as ng-eNB 162A and ng-eNB 162B(collectively ng-eNBs 162). The gNBs 160 and ng-eNBs 162 may be moregenerically referred to as base stations. The gNBs 160 and ng-eNBs 162may include one or more sets of antennas for communicating with the UEs156 over an air interface. For example, one or more of the gNBs 160and/or one or more of the ng-eNBs 162 may include three sets of antennasto respectively control three cells (or sectors). Together, the cells ofthe gNBs 160 and the ng-eNBs 162 may provide radio coverage to the UEs156 over a wide geographic area to support UE mobility.

As shown in FIG. 1B, the gNBs 160 and/or the ng-eNBs 162 may beconnected to the 5G-CN 152 by means of an NG interface and to other basestations by an Xn interface. The NG and Xn interfaces may be establishedusing direct physical connections and/or indirect connections over anunderlying transport network, such as an internet protocol (IP)transport network. The gNBs 160 and/or the ng-eNBs 162 may be connectedto the UEs 156 by means of a Uu interface. For example, as illustratedin FIG. 1B, gNB 160A may be connected to the UE 156A by means of a Uuinterface. The NG, Xn, and Uu interfaces are associated with a protocolstack. The protocol stacks associated with the interfaces may be used bythe network elements in FIG. 1B to exchange data and signaling messagesand may include two planes: a user plane and a control plane. The userplane may handle data of interest to a user. The control plane mayhandle signaling messages of interest to the network elements.

The gNBs 160 and/or the ng-eNBs 162 may be connected to one or moreAMF/UPF functions of the 5G-CN 152, such as the AMF/UPF 158, by means ofone or more NG interfaces. For example, the gNB 160A may be connected tothe UPF 158B of the AMF/UPF 158 by means of an NG-User plane (NG-U)interface. The NG-U interface may provide delivery (e.g., non-guaranteeddelivery) of user plane PDUs between the gNB 160A and the UPF 158B. ThegNB 160A may be connected to the AMF 158A by means of an NG-Controlplane (NG-C) interface. The NG-C interface may provide, for example, NGinterface management, UE context management, UE mobility management,transport of NAS messages, paging, PDU session management, andconfiguration transfer and/or warning message transmission.

The gNBs 160 may provide NR user plane and control plane protocolterminations towards the UEs 156 over the Uu interface. For example, thegNB 160A may provide NR user plane and control plane protocolterminations toward the UE 156A over a Uu interface associated with afirst protocol stack. The ng-eNBs 162 may provide Evolved UMTSTerrestrial Radio Access (E-UTRA) user plane and control plane protocolterminations towards the UEs 156 over a Uu interface, where E-UTRArefers to the 3GPP 4G radio-access technology. For example, the ng-eNB162B may provide E-UTRA user plane and control plane protocolterminations towards the UE 156B over a Uu interface associated with asecond protocol stack.

The 5G-CN 152 was described as being configured to handle NR and 4Gradio accesses. It will be appreciated by one of ordinary skill in theart that it may be possible for NR to connect to a 4G core network in amode known as “non-standalone operation.” In non-standalone operation, a4G core network is used to provide (or at least support) control-planefunctionality (e.g., initial access, mobility, and paging). Althoughonly one AMF/UPF 158 is shown in FIG. 1B, one gNB or ng-eNB may beconnected to multiple AMF/UPF nodes to provide redundancy and/or to loadshare across the multiple AMF/UPF nodes.

As discussed, an interface (e.g., Uu, Xn, and NG interfaces) between thenetwork elements in FIG. 1B may be associated with a protocol stack thatthe network elements use to exchange data and signaling messages. Aprotocol stack may include two planes: a user plane and a control plane.The user plane may handle data of interest to a user, and the controlplane may handle signaling messages of interest to the network elements.

FIG. 2A and FIG. 2B respectively illustrate examples of NR user planeand NR control plane protocol stacks for the Uu interface that liesbetween a UE 210 and a gNB 220. The protocol stacks illustrated in FIG.2A and FIG. 2B may be the same or similar to those used for the Uuinterface between, for example, the UE 156A and the gNB 160A shown inFIG. 1B.

FIG. 2A illustrates a NR user plane protocol stack comprising fivelayers implemented in the UE 210 and the gNB 220. At the bottom of theprotocol stack, physical layers (PHYs) 211 and 221 may provide transportservices to the higher layers of the protocol stack and may correspondto layer 1 of the Open Systems Interconnection (OSI) model. The nextfour protocols above PHYs 211 and 221 comprise media access controllayers (MACs) 212 and 222, radio link control layers (RLCs) 213 and 223,packet data convergence protocol layers (PDCPs) 214 and 224, and servicedata application protocol layers (SDAPs) 215 and 225. Together, thesefour protocols may make up layer 2, or the data link layer, of the OSImodel.

FIG. 3 illustrates an example of services provided between protocollayers of the NR user plane protocol stack. Starting from the top ofFIG. 2A and FIG. 3 , the SDAPs 215 and 225 may perform QoS flowhandling. The UE 210 may receive services through a PDU session, whichmay be a logical connection between the UE 210 and a DN. The PDU sessionmay have one or more QoS flows. A UPF of a CN (e.g., the UPF 158B) maymap IP packets to the one or more QoS flows of the PDU session based onQoS requirements (e.g., in terms of delay, data rate, and/or errorrate). The SDAPs 215 and 225 may perform mapping/de-mapping between theone or more QoS flows and one or more data radio bearers. Themapping/de-mapping between the QoS flows and the data radio bearers maybe determined by the SDAP 225 at the gNB 220. The SDAP 215 at the UE 210may be informed of the mapping between the QoS flows and the data radiobearers through reflective mapping or control signaling received fromthe gNB 220. For reflective mapping, the SDAP 225 at the gNB 220 maymark the downlink packets with a QoS flow indicator (QFI), which may beobserved by the SDAP 215 at the UE 210 to determine themapping/de-mapping between the QoS flows and the data radio bearers.

The PDCPs 214 and 224 may perform header compression/decompression toreduce the amount of data that needs to be transmitted over the airinterface, ciphering/deciphering to prevent unauthorized decoding ofdata transmitted over the air interface, and integrity protection (toensure control messages originate from intended sources. The PDCPs 214and 224 may perform retransmissions of undelivered packets, in-sequencedelivery and reordering of packets, and removal of packets received induplicate due to, for example, an intra-gNB handover. The PDCPs 214 and224 may perform packet duplication to improve the likelihood of thepacket being received and, at the receiver, remove any duplicatepackets. Packet duplication may be useful for services that require highreliability.

Although not shown in FIG. 3 , PDCPs 214 and 224 may performmapping/de-mapping between a split radio bearer and RLC channels in adual connectivity scenario. Dual connectivity is a technique that allowsa UE to connect to two cells or, more generally, two cell groups: amaster cell group (MCG) and a secondary cell group (SCG). A split beareris when a single radio bearer, such as one of the radio bearers providedby the PDCPs 214 and 224 as a service to the SDAPs 215 and 225, ishandled by cell groups in dual connectivity. The PDCPs 214 and 224 maymap/de-map the split radio bearer between RLC channels belonging to cellgroups.

The RLCs 213 and 223 may perform segmentation, retransmission throughAutomatic Repeat Request (ARQ), and removal of duplicate data unitsreceived from MACs 212 and 222, respectively. The RLCs 213 and 223 maysupport three transmission modes: transparent mode (TM); unacknowledgedmode (UM); and acknowledged mode (AM). Based on the transmission mode anRLC is operating, the RLC may perform one or more of the notedfunctions. The RLC configuration may be per logical channel with nodependency on numerologies and/or Transmission Time Interval (TTI)durations. As shown in FIG. 3 , the RLCs 213 and 223 may provide RLCchannels as a service to PDCPs 214 and 224, respectively.

The MACs 212 and 222 may perform multiplexing/demultiplexing of logicalchannels and/or mapping between logical channels and transport channels.The multiplexing/demultiplexing may include multiplexing/demultiplexingof data units, belonging to the one or more logical channels, into/fromTransport Blocks (TBs) delivered to/from the PHYs 211 and 221. The MAC222 may be configured to perform scheduling, scheduling informationreporting, and priority handling between UEs by means of dynamicscheduling. Scheduling may be performed in the gNB 220 (at the MAC 222)for downlink and uplink. The MACs 212 and 222 may be configured toperform error correction through Hybrid Automatic Repeat Request (HARQ)(e.g., one HARQ entity per carrier in case of Carrier Aggregation (CA)),priority handling between logical channels of the UE 210 by means oflogical channel prioritization, and/or padding. The MACs 212 and 222 maysupport one or more numerologies and/or transmission timings. In anexample, mapping restrictions in a logical channel prioritization maycontrol which numerology and/or transmission timing a logical channelmay use. As shown in FIG. 3 , the MACs 212 and 222 may provide logicalchannels as a service to the RLCs 213 and 223.

The PHYs 211 and 221 may perform mapping of transport channels tophysical channels and digital and analog signal processing functions forsending and receiving information over the air interface. These digitaland analog signal processing functions may include, for example,coding/decoding and modulation/demodulation. The PHYs 211 and 221 mayperform multi-antenna mapping. As shown in FIG. 3 , the PHYs 211 and 221may provide one or more transport channels as a service to the MACs 212and 222.

FIG. 4A illustrates an example downlink data flow through the NR userplane protocol stack. FIG. 4A illustrates a downlink data flow of threeIP packets (n, n+1, and m) through the NR user plane protocol stack togenerate two TBs at the gNB 220. An uplink data flow through the NR userplane protocol stack may be similar to the downlink data flow depictedin FIG. 4A.

The downlink data flow of FIG. 4A begins when SDAP 225 receives thethree IP packets from one or more QoS flows and maps the three packetsto radio bearers. In FIG. 4A, the SDAP 225 maps IP packets n and n+1 toa first radio bearer 402 and maps IP packet m to a second radio bearer404. An SDAP header (labeled with an “H” in FIG. 4A) is added to an IPpacket. The data unit from/to a higher protocol layer is referred to asa service data unit (SDU) of the lower protocol layer and the data unitto/from a lower protocol layer is referred to as a protocol data unit(PDU) of the higher protocol layer. As shown in FIG. 4A, the data unitfrom the SDAP 225 is an SDU of lower protocol layer PDCP 224 and is aPDU of the SDAP 225.

The remaining protocol layers in FIG. 4A may perform their associatedfunctionality (e.g., with respect to FIG. 3 ), add correspondingheaders, and forward their respective outputs to the next lower layer.For example, the PDCP 224 may perform IP-header compression andciphering and forward its output to the RLC 223. The RLC 223 mayoptionally perform segmentation (e.g., as shown for IP packet m in FIG.4A) and forward its output to the MAC 222. The MAC 222 may multiplex anumber of RLC PDUs and may attach a MAC subheader to an RLC PDU to forma transport block. In NR, the MAC subheaders may be distributed acrossthe MAC PDU, as illustrated in FIG. 4A. In LTE, the MAC subheaders maybe entirely located at the beginning of the MAC PDU. The NR MAC PDUstructure may reduce processing time and associated latency because theMAC PDU subheaders may be computed before the full MAC PDU is assembled.

FIG. 4B illustrates an example format of a MAC subheader in a MAC PDU.The MAC subheader includes: an SDU length field for indicating thelength (e.g., in bytes) of the MAC SDU to which the MAC subheadercorresponds; a logical channel identifier (LCID) field for identifyingthe logical channel from which the MAC SDU originated to aid in thedemultiplexing process; a flag (F) for indicating the size of the SDUlength field; and a reserved bit (R) field for future use.

FIG. 4B further illustrates MAC control elements (CEs) inserted into theMAC PDU by a MAC, such as MAC 223 or MAC 222. For example, FIG. 4Billustrates two MAC CEs inserted into the MAC PDU. MAC CEs may beinserted at the beginning of a MAC PDU for downlink transmissions (asshown in FIG. 4B) and at the end of a MAC PDU for uplink transmissions.MAC CEs may be used for in-band control signaling. Example MAC CEsinclude: scheduling-related MAC CEs, such as buffer status reports andpower headroom reports; activation/deactivation MAC CEs, such as thosefor activation/deactivation of PDCP duplication detection, channel stateinformation (CSI) reporting, sounding reference signal (SRS)transmission, and prior configured components; discontinuous reception(DRX) related MAC CEs; timing advance MAC CEs; and random access relatedMAC CEs. A MAC CE may be preceded by a MAC subheader with a similarformat as described for MAC SDUs and may be identified with a reservedvalue in the LCID field that indicates the type of control informationincluded in the MAC CE.

Before describing the NR control plane protocol stack, logical channels,transport channels, and physical channels are first described as well asa mapping between the channel types. One or more of the channels may beused to carry out functions associated with the NR control planeprotocol stack described later below.

FIG. 5A and FIG. 5B illustrate, for downlink and uplink respectively, amapping between logical channels, transport channels, and physicalchannels. Information is passed through channels between the RLC, theMAC, and the PHY of the NR protocol stack. A logical channel may be usedbetween the RLC and the MAC and may be classified as a control channelthat carries control and configuration information in the NR controlplane or as a traffic channel that carries data in the NR user plane. Alogical channel may be classified as a dedicated logical channel that isdedicated to a specific UE or as a common logical channel that may beused by more than one UE. A logical channel may also be defined by thetype of information it carries. The set of logical channels defined byNR include, for example:

-   -   a paging control channel (PCCH) for carrying paging messages        used to page a UE whose location is not known to the network on        a cell level;    -   a broadcast control channel (BCCH) for carrying system        information messages in the form of a master information block        (MIB) and several system information blocks (SIBs), wherein the        system information messages may be used by the UEs to obtain        information about how a cell is configured and how to operate        within the cell;    -   a common control channel (CCCH) for carrying control messages        together with random access;    -   a dedicated control channel (DCCH) for carrying control messages        to/from a specific the UE to configure the UE; and    -   a dedicated traffic channel (DTCH) for carrying user data        to/from a specific the UE.

Transport channels are used between the MAC and PHY layers and may bedefined by how the information they carry is transmitted over the airinterface. The set of transport channels defined by NR include, forexample:

-   -   a paging channel (PCH) for carrying paging messages that        originated from the PCCH;    -   a broadcast channel (BCH) for carrying the MIB from the BCCH;    -   a downlink shared channel (DL-SCH) for carrying downlink data        and signaling messages, including the SIBs from the BCCH;    -   an uplink shared channel (UL-SCH) for carrying uplink data and        signaling messages; and    -   a random access channel (RACH) for allowing a UE to contact the        network without any prior scheduling.

The PHY may use physical channels to pass information between processinglevels of the PHY. A physical channel may have an associated set oftime-frequency resources for carrying the information of one or moretransport channels. The PHY may generate control information to supportthe low-level operation of the PHY and provide the control informationto the lower levels of the PHY via physical control channels, known asL1/L2 control channels. The set of physical channels and physicalcontrol channels defined by NR include, for example:

-   -   a physical broadcast channel (PBCH) for carrying the MIB from        the BCH;    -   a physical downlink shared channel (PDSCH) for carrying downlink        data and signaling messages from the DL-SCH, as well as paging        messages from the PCH;    -   a physical downlink control channel (PDCCH) for carrying        downlink control information (DCI), which may include downlink        scheduling commands, uplink scheduling grants, and uplink power        control commands;    -   a physical uplink shared channel (PUSCH) for carrying uplink        data and signaling messages from the UL-SCH and in some        instances uplink control information (UCI) as described below;    -   a physical uplink control channel (PUCCH) for carrying UCI,        which may include HARQ acknowledgments, channel quality        indicators (CQI), pre-coding matrix indicators (PMI), rank        indicators (RI), and scheduling requests (SR); and    -   a physical random access channel (PRACH) for random access.

Similar to the physical control channels, the physical layer generatesphysical signals to support the low-level operation of the physicallayer. As shown in FIG. 5A and FIG. 5B, the physical layer signalsdefined by NR include: primary synchronization signals (PSS), secondarysynchronization signals (SSS), channel state information referencesignals (CSI-RS), demodulation reference signals (DMRS), soundingreference signals (SRS), and phase-tracking reference signals (PT-RS).These physical layer signals will be described in greater detail below.

Control Plane Protocol Stack

FIG. 2B illustrates an example NR control plane protocol stack. As shownin FIG. 2B, the NR control plane protocol stack may use the same/similarfirst four protocol layers as the example NR user plane protocol stack.These four protocol layers include the PHYs 211 and 221, the MACs 212and 222, the RLCs 213 and 223, and the PDCPs 214 and 224. Instead ofhaving the SDAPs 215 and 225 at the top of the stack as in the NR userplane protocol stack, the NR control plane stack has radio resourcecontrols (RRCs) 216 and 226 and NAS protocols 217 and 237 at the top ofthe NR control plane protocol stack.

The NAS protocols 217 and 237 may provide control plane functionalitybetween the UE 210 and the AMF 230 (e.g., the AMF 158A) or, moregenerally, between the UE 210 and the CN. The NAS protocols 217 and 237may provide control plane functionality between the UE 210 and the AMF230 via signaling messages, referred to as NAS messages. There is nodirect path between the UE 210 and the AMF 230 through which the NASmessages can be transported. The NAS messages may be transported usingthe AS of the Uu and NG interfaces. NAS protocols 217 and 237 mayprovide control plane functionality such as authentication, security,connection setup, mobility management, and session management.

The RRCs 216 and 226 may provide control plane functionality between theUE 210 and the gNB 220 or, more generally, between the UE 210 and theRAN. The RRCs 216 and 226 may provide control plane functionalitybetween the UE 210 and the gNB 220 via signaling messages, referred toas RRC messages. RRC messages may be transmitted between the UE 210 andthe RAN using signaling radio bearers and the same/similar PDCP, RLC,MAC, and PHY protocol layers. The MAC may multiplex control-plane anduser-plane data into the same transport block (TB). The RRCs 216 and 226may provide control plane functionality such as: broadcast of systeminformation related to AS and NAS; paging initiated by the CN or theRAN; establishment, maintenance and release of an RRC connection betweenthe UE 210 and the RAN; security functions including key management;establishment, configuration, maintenance and release of signaling radiobearers and data radio bearers; mobility functions; QoS managementfunctions; the UE measurement reporting and control of the reporting;detection of and recovery from radio link failure (RLF); and/or NASmessage transfer. As part of establishing an RRC connection, RRCs 216and 226 may establish an RRC context, which may involve configuringparameters for communication between the UE 210 and the RAN.

FIG. 6 is an example diagram showing RRC state transitions of a UE. TheUE may be the same or similar to the wireless device 106 depicted inFIG. 1A, the UE 210 depicted in FIG. 2A and FIG. 2B, or any otherwireless device described in the present disclosure. As illustrated inFIG. 6 , a UE may be in at least one of three RRC states: RRC connected602 (e.g., RRC_CONNECTED), RRC idle 604 (e.g., RRC_IDLE), and RRCinactive 606 (e.g., RRC_INACTIVE).

In RRC connected 602, the UE has an established RRC context and may haveat least one RRC connection with a base station. The base station may besimilar to one of the one or more base stations included in the RAN 104depicted in FIG. 1A, one of the gNBs 160 or ng-eNBs 162 depicted in FIG.1B, the gNB 220 depicted in FIG. 2A and FIG. 2B, or any other basestation described in the present disclosure. The base station with whichthe UE is connected may have the RRC context for the UE. The RRCcontext, referred to as the UE context, may comprise parameters forcommunication between the UE and the base station. These parameters mayinclude, for example: one or more AS contexts; one or more radio linkconfiguration parameters; bearer configuration information (e.g.,relating to a data radio bearer, signaling radio bearer, logicalchannel, QoS flow, and/or PDU session); security information; and/orPHY, MAC, RLC, PDCP, and/or SDAP layer configuration information. Whilein RRC connected 602, mobility of the UE may be managed by the RAN(e.g., the RAN 104 or the NG-RAN 154). The UE may measure the signallevels (e.g., reference signal levels) from a serving cell andneighboring cells and report these measurements to the base stationcurrently serving the UE. The UE's serving base station may request ahandover to a cell of one of the neighboring base stations based on thereported measurements. The RRC state may transition from RRC connected602 to RRC idle 604 through a connection release procedure 608 or to RRCinactive 606 through a connection inactivation procedure 610.

In RRC idle 604, an RRC context may not be established for the UE. InRRC idle 604, the UE may not have an RRC connection with the basestation. While in RRC idle 604, the UE may be in a sleep state for themajority of the time (e.g., to conserve battery power). The UE may wakeup periodically (e.g., once in every discontinuous reception cycle) tomonitor for paging messages from the RAN. Mobility of the UE may bemanaged by the UE through a procedure known as cell reselection. The RRCstate may transition from RRC idle 604 to RRC connected 602 through aconnection establishment procedure 612, which may involve a randomaccess procedure as discussed in greater detail below.

In RRC inactive 606, the RRC context previously established ismaintained in the UE and the base station. This allows for a fasttransition to RRC connected 602 with reduced signaling overhead ascompared to the transition from RRC idle 604 to RRC connected 602. Whilein RRC inactive 606, the UE may be in a sleep state and mobility of theUE may be managed by the UE through cell reselection. The RRC state maytransition from RRC inactive 606 to RRC connected 602 through aconnection resume procedure 614 or to RRC idle 604 though a connectionrelease procedure 616 that may be the same as or similar to connectionrelease procedure 608.

An RRC state may be associated with a mobility management mechanism. InRRC idle 604 and RRC inactive 606, mobility is managed by the UE throughcell reselection. The purpose of mobility management in RRC idle 604 andRRC inactive 606 is to allow the network to be able to notify the UE ofan event via a paging message without having to broadcast the pagingmessage over the entire mobile communications network. The mobilitymanagement mechanism used in RRC idle 604 and RRC inactive 606 may allowthe network to track the UE on a cell-group level so that the pagingmessage may be broadcast over the cells of the cell group that the UEcurrently resides within instead of the entire mobile communicationnetwork. The mobility management mechanisms for RRC idle 604 and RRCinactive 606 track the UE on a cell-group level. They may do so usingdifferent granularities of grouping. For example, there may be threelevels of cell-grouping granularity: individual cells; cells within aRAN area identified by a RAN area identifier (RAI); and cells within agroup of RAN areas, referred to as a tracking area and identified by atracking area identifier (TAI).

Tracking areas may be used to track the UE at the CN level. The CN(e.g., the CN 102 or the 5G-CN 152) may provide the UE with a list ofTAIs associated with a UE registration area. If the UE moves, throughcell reselection, to a cell associated with a TAI not included in thelist of TAIs associated with the UE registration area, the UE mayperform a registration update with the CN to allow the CN to update theUE's location and provide the UE with a new the UE registration area.

RAN areas may be used to track the UE at the RAN level. For a UE in RRCinactive 606 state, the UE may be assigned a RAN notification area. ARAN notification area may comprise one or more cell identities, a listof RAIs, or a list of TAIs. In an example, a base station may belong toone or more RAN notification areas. In an example, a cell may belong toone or more RAN notification areas. If the UE moves, through cellreselection, to a cell not included in the RAN notification areaassigned to the UE, the UE may perform a notification area update withthe RAN to update the UE's RAN notification area.

A base station storing an RRC context for a UE or a last serving basestation of the UE may be referred to as an anchor base station. Ananchor base station may maintain an RRC context for the UE at leastduring a period of time that the UE stays in a RAN notification area ofthe anchor base station and/or during a period of time that the UE staysin RRC inactive 606.

A gNB, such as gNBs 160 in FIG. 1B, may be split in two parts: a centralunit (gNB-CU), and one or more distributed units (gNB-DU). A gNB-CU maybe coupled to one or more gNB-DUs using an F1 interface. The gNB-CU maycomprise the RRC, the PDCP, and the SDAP. A gNB-DU may comprise the RLC,the MAC, and the PHY.

In NR, the physical signals and physical channels (discussed withrespect to FIG. 5A and FIG. 5B) may be mapped onto orthogonal frequencydivisional multiplexing (OFDM) symbols.

OFDM is a multicarrier communication scheme that transmits data over Forthogonal subcarriers (or tones). Before transmission, the data may bemapped to a series of complex symbols (e.g., M-quadrature amplitudemodulation (M-QAM) or M-phase shift keying (M-PSK) symbols), referred toas source symbols, and divided into F parallel symbol streams. The Fparallel symbol streams may be treated as though they are in thefrequency domain and used as inputs to an Inverse Fast Fourier Transform(IFFT) block that transforms them into the time domain. The IFFT blockmay take in F source symbols at a time, one from each of the F parallelsymbol streams, and use each source symbol to modulate the amplitude andphase of one of F sinusoidal basis functions that correspond to the Forthogonal subcarriers. The output of the IFFT block may be Ftime-domain samples that represent the summation of the F orthogonalsubcarriers. The F time-domain samples may form a single OFDM symbol.After some processing (e.g., addition of a cyclic prefix) andup-conversion, an OFDM symbol provided by the IFFT block may betransmitted over the air interface on a carrier frequency. The Fparallel symbol streams may be mixed using an FFT block before beingprocessed by the IFFT block. This operation produces Discrete FourierTransform (DFT)-precoded OFDM symbols and may be used by UEs in theuplink to reduce the peak to average power ratio (PAPR). Inverseprocessing may be performed on the OFDM symbol at a receiver using anFFT block to recover the data mapped to the source symbols.

FIG. 7 illustrates an example configuration of an NR frame into whichOFDM symbols are grouped. An NR frame may be identified by a systemframe number (SFN). The SFN may repeat with a period of 1024 frames. Asillustrated, one NR frame may be 10 milliseconds (ms) in duration andmay include 10 subframes that are 1 ms in duration. A subframe may bedivided into slots that include, for example, 14 OFDM symbols per slot.

The duration of a slot may depend on the numerology used for the OFDMsymbols of the slot. In NR, a flexible numerology is supported toaccommodate different cell deployments (e.g., cells with carrierfrequencies below 1 GHz up to cells with carrier frequencies in themm-wave range). A numerology may be defined in terms of subcarrierspacing and cyclic prefix duration. For a numerology in NR, subcarrierspacings may be scaled up by powers of two from a baseline subcarrierspacing of 15 kHz, and cyclic prefix durations may be scaled down bypowers of two from a baseline cyclic prefix duration of 4.7 s. Forexample, NR defines numerologies with the following subcarrierspacing/cyclic prefix duration combinations: 15 kHz/4.7 s; 30 kHz/2.3 s;60 kHz/1.2 s; 120 kHz/0.59 s; and 240 kHz/0.29 s.

A slot may have a fixed number of OFDM symbols (e.g., 14 OFDM symbols).A numerology with a higher subcarrier spacing has a shorter slotduration and, correspondingly, more slots per subframe. FIG. 7illustrates this numerology-dependent slot duration andslots-per-subframe transmission structure (the numerology with asubcarrier spacing of 240 kHz is not shown in FIG. 7 for ease ofillustration). A subframe in NR may be used as a numerology-independenttime reference, while a slot may be used as the unit upon which uplinkand downlink transmissions are scheduled. To support low latency,scheduling in NR may be decoupled from the slot duration and start atany OFDM symbol and last for as many symbols as needed for atransmission. These partial slot transmissions may be referred to asmini-slot or subslot transmissions.

FIG. 8 illustrates an example configuration of a slot in the time andfrequency domain for an NR carrier. The slot includes resource elements(REs) and resource blocks (RBs). An RE is the smallest physical resourcein NR. An RE spans one OFDM symbol in the time domain by one subcarrierin the frequency domain as shown in FIG. 8 . An RB spans twelveconsecutive REs in the frequency domain as shown in FIG. 8 . An NRcarrier may be limited to a width of 275 RBs or 275×12=3300 subcarriers.Such a limitation, if used, may limit the NR carrier to 50, 100, 200,and 400 MHz for subcarrier spacings of 15, 30, 60, and 120 kHz,respectively, where the 400 MHz bandwidth may be set based on a 400 MHzper carrier bandwidth limit.

FIG. 8 illustrates a single numerology being used across the entirebandwidth of the NR carrier. In other example configurations, multiplenumerologies may be supported on the same carrier.

NR may support wide carrier bandwidths (e.g., up to 400 MHz for asubcarrier spacing of 120 kHz). Not all UEs may be able to receive thefull carrier bandwidth (e.g., due to hardware limitations). Also,receiving the full carrier bandwidth may be prohibitive in terms of UEpower consumption. In an example, to reduce power consumption and/or forother purposes, a UE may adapt the size of the UE's receive bandwidthbased on the amount of traffic the UE is scheduled to receive. This isreferred to as bandwidth adaptation.

NR defines bandwidth parts (BWPs) to support UEs not capable ofreceiving the full carrier bandwidth and to support bandwidthadaptation. In an example, a BWP may be defined by a subset ofcontiguous RBs on a carrier. A UE may be configured (e.g., via RRClayer) with one or more downlink BWPs and one or more uplink BWPs perserving cell (e.g., up to four downlink BWPs and up to four uplink BWPsper serving cell). At a given time, one or more of the configured BWPsfor a serving cell may be active. These one or more BWPs may be referredto as active BWPs of the serving cell. When a serving cell is configuredwith a secondary uplink carrier, the serving cell may have one or morefirst active BWPs in the uplink carrier and one or more second activeBWPs in the secondary uplink carrier.

For unpaired spectra, a downlink BWP from a set of configured downlinkBWPs may be linked with an uplink BWP from a set of configured uplinkBWPs if a downlink BWP index of the downlink BWP and an uplink BWP indexof the uplink BWP are the same. For unpaired spectra, a UE may expectthat a center frequency for a downlink BWP is the same as a centerfrequency for an uplink BWP.

For a downlink BWP in a set of configured downlink BWPs on a primarycell (PCell), a base station may configure a UE with one or more controlresource sets (CORESETs) for at least one search space. A search spaceis a set of locations in the time and frequency domains where the UE mayfind control information. The search space may be a UE-specific searchspace or a common search space (potentially usable by a plurality ofUEs). For example, a base station may configure a UE with a commonsearch space, on a PCell or on a primary secondary cell (PSCell), in anactive downlink BWP.

For an uplink BWP in a set of configured uplink BWPs, a BS may configurea UE with one or more resource sets for one or more PUCCH transmissions.A UE may receive downlink receptions (e.g., PDCCH or PDSCH) in adownlink BWP according to a configured numerology (e.g., subcarrierspacing and cyclic prefix duration) for the downlink BWP. The UE maytransmit uplink transmissions (e.g., PUCCH or PUSCH) in an uplink BWPaccording to a configured numerology (e.g., subcarrier spacing andcyclic prefix length for the uplink BWP).

One or more BWP indicator fields may be provided in Downlink ControlInformation (DCI). A value of a BWP indicator field may indicate whichBWP in a set of configured BWPs is an active downlink BWP for one ormore downlink receptions. The value of the one or more BWP indicatorfields may indicate an active uplink BWP for one or more uplinktransmissions.

A base station may semi-statically configure a UE with a defaultdownlink BWP within a set of configured downlink BWPs associated with aPCell. If the base station does not provide the default downlink BWP tothe UE, the default downlink BWP may be an initial active downlink BWP.The UE may determine which BWP is the initial active downlink BWP basedon a CORESET configuration obtained using the PBCH.

A base station may configure a UE with a BWP inactivity timer value fora PCell. The UE may start or restart a BWP inactivity timer at anyappropriate time. For example, the UE may start or restart the BWPinactivity timer (a) when the UE detects a DCI indicating an activedownlink BWP other than a default downlink BWP for a paired spectraoperation; or (b) when a UE detects a DCI indicating an active downlinkBWP or active uplink BWP other than a default downlink BWP or uplink BWPfor an unpaired spectra operation. If the UE does not detect DCI duringan interval of time (e.g., 1 ms or 0.5 ms), the UE may run the BWPinactivity timer toward expiration (for example, increment from zero tothe BWP inactivity timer value, or decrement from the BWP inactivitytimer value to zero). When the BWP inactivity timer expires, the UE mayswitch from the active downlink BWP to the default downlink BWP.

In an example, a base station may semi-statically configure a UE withone or more BWPs. A UE may switch an active BWP from a first BWP to asecond BWP in response to receiving a DCI indicating the second BWP asan active BWP and/or in response to an expiry of the BWP inactivitytimer (e.g., if the second BWP is the default BWP).

Downlink and uplink BWP switching (where BWP switching refers toswitching from a currently active BWP to a not currently active BWP) maybe performed independently in paired spectra. In unpaired spectra,downlink and uplink BWP switching may be performed simultaneously.Switching between configured BWPs may occur based on RRC signaling, DCI,expiration of a BWP inactivity timer, and/or an initiation of randomaccess.

FIG. 9 illustrates an example of bandwidth adaptation using threeconfigured BWPs for an NR carrier. A UE configured with the three BWPsmay switch from one BWP to another BWP at a switching point. In theexample illustrated in FIG. 9 , the BWPs include: a BWP 902 with abandwidth of 40 MHz and a subcarrier spacing of 15 kHz; a BWP 904 with abandwidth of 10 MHz and a subcarrier spacing of 15 kHz; and a BWP 906with a bandwidth of 20 MHz and a subcarrier spacing of 60 kHz. The BWP902 may be an initial active BWP, and the BWP 904 may be a default BWP.The UE may switch between BWPs at switching points. In the example ofFIG. 9 , the UE may switch from the BWP 902 to the BWP 904 at aswitching point 908. The switching at the switching point 908 may occurfor any suitable reason, for example, in response to an expiry of a BWPinactivity timer (indicating switching to the default BWP) and/or inresponse to receiving a DCI indicating BWP 904 as the active BWP. The UEmay switch at a switching point 910 from active BWP 904 to BWP 906 inresponse receiving a DCI indicating BWP 906 as the active BWP. The UEmay switch at a switching point 912 from active BWP 906 to BWP 904 inresponse to an expiry of a BWP inactivity timer and/or in responsereceiving a DCI indicating BWP 904 as the active BWP. The UE may switchat a switching point 914 from active BWP 904 to BWP 902 in responsereceiving a DCI indicating BWP 902 as the active BWP.

If a UE is configured for a secondary cell with a default downlink BWPin a set of configured downlink BWPs and a timer value, UE proceduresfor switching BWPs on a secondary cell may be the same/similar as thoseon a primary cell. For example, the UE may use the timer value and thedefault downlink BWP for the secondary cell in the same/similar manneras the UE would use these values for a primary cell.

To provide for greater data rates, two or more carriers can beaggregated and simultaneously transmitted to/from the same UE usingcarrier aggregation (CA). The aggregated carriers in CA may be referredto as component carriers (CCs). When CA is used, there are a number ofserving cells for the UE, one for a CC. The CCs may have threeconfigurations in the frequency domain.

FIG. 10A illustrates the three CA configurations with two CCs. In theintraband, contiguous configuration 1002, the two CCs are aggregated inthe same frequency band (frequency band A) and are located directlyadjacent to each other within the frequency band. In the intraband,non-contiguous configuration 1004, the two CCs are aggregated in thesame frequency band (frequency band A) and are separated in thefrequency band by a gap. In the interband configuration 1006, the twoCCs are located in frequency bands (frequency band A and frequency bandB).

In an example, up to 32 CCs may be aggregated. The aggregated CCs mayhave the same or different bandwidths, subcarrier spacing, and/orduplexing schemes (TDD or FDD). A serving cell for a UE using CA mayhave a downlink CC. For FDD, one or more uplink CCs may be optionallyconfigured for a serving cell. The ability to aggregate more downlinkcarriers than uplink carriers may be useful, for example, when the UEhas more data traffic in the downlink than in the uplink.

When CA is used, one of the aggregated cells for a UE may be referred toas a primary cell (PCell). The PCell may be the serving cell that the UEinitially connects to at RRC connection establishment, reestablishment,and/or handover. The PCell may provide the UE with NAS mobilityinformation and the security input. UEs may have different PCells. Inthe downlink, the carrier corresponding to the PCell may be referred toas the downlink primary CC (DL PCC). In the uplink, the carriercorresponding to the PCell may be referred to as the uplink primary CC(UL PCC). The other aggregated cells for the UE may be referred to assecondary cells (SCells). In an example, the SCells may be configuredafter the PCell is configured for the UE. For example, an SCell may beconfigured through an RRC Connection Reconfiguration procedure. In thedownlink, the carrier corresponding to an SCell may be referred to as adownlink secondary CC (DL SCC). In the uplink, the carrier correspondingto the SCell may be referred to as the uplink secondary CC (UL SCC).

Configured SCells for a UE may be activated and deactivated based on,for example, traffic and channel conditions. Deactivation of an SCellmay mean that PDCCH and PDSCH reception on the SCell is stopped andPUSCH, SRS, and CQI transmissions on the SCell are stopped. ConfiguredSCells may be activated and deactivated using a MAC CE with respect toFIG. 4B. For example, a MAC CE may use a bitmap (e.g., one bit perSCell) to indicate which SCells (e.g., in a subset of configured SCells)for the UE are activated or deactivated. Configured SCells may bedeactivated in response to an expiration of an SCell deactivation timer(e.g., one SCell deactivation timer per SCell).

Downlink control information, such as scheduling assignments andscheduling grants, for a cell may be transmitted on the cellcorresponding to the assignments and grants, which is known asself-scheduling. The DCI for the cell may be transmitted on anothercell, which is known as cross-carrier scheduling. Uplink controlinformation (e.g., HARQ acknowledgments and channel state feedback, suchas CQI, PMI, and/or RI) for aggregated cells may be transmitted on thePUCCH of the PCell. For a larger number of aggregated downlink CCs, thePUCCH of the PCell may become overloaded. Cells may be divided intomultiple PUCCH groups.

FIG. 10B illustrates an example of how aggregated cells may beconfigured into one or more PUCCH groups. A PUCCH group 1010 and a PUCCHgroup 1050 may include one or more downlink CCs, respectively. In theexample of FIG. 10B, the PUCCH group 1010 includes three downlink CCs: aPCell 1011, an SCell 1012, and an SCell 1013. The PUCCH group 1050includes three downlink CCs in the present example: a PCell 1051, anSCell 1052, and an SCell 1053. One or more uplink CCs may be configuredas a PCell 1021, an SCell 1022, and an SCell 1023. One or more otheruplink CCs may be configured as a primary Scell (PSCell) 1061, an SCell1062, and an SCell 1063. Uplink control information (UCI) related to thedownlink CCs of the PUCCH group 1010, shown as UCI 1031, UCI 1032, andUCI 1033, may be transmitted in the uplink of the PCell 1021. Uplinkcontrol information (UCI) related to the downlink CCs of the PUCCH group1050, shown as UCI 1071, UCI 1072, and UCI 1073, may be transmitted inthe uplink of the PSCell 1061. In an example, if the aggregated cellsdepicted in FIG. 10B were not divided into the PUCCH group 1010 and thePUCCH group 1050, a single uplink PCell to transmit UCI relating to thedownlink CCs, and the PCell may become overloaded. By dividingtransmissions of UCI between the PCell 1021 and the PSCell 1061,overloading may be prevented.

A cell, comprising a downlink carrier and optionally an uplink carrier,may be assigned with a physical cell ID and a cell index. The physicalcell ID or the cell index may identify a downlink carrier and/or anuplink carrier of the cell, for example, depending on the context inwhich the physical cell ID is used. A physical cell ID may be determinedusing a synchronization signal transmitted on a downlink componentcarrier. A cell index may be determined using RRC messages. In thedisclosure, a physical cell ID may be referred to as a carrier ID, and acell index may be referred to as a carrier index. For example, when thedisclosure refers to a first physical cell ID for a first downlinkcarrier, the disclosure may mean the first physical cell ID is for acell comprising the first downlink carrier. The same/similar concept mayapply to, for example, a carrier activation. When the disclosureindicates that a first carrier is activated, the specification may meanthat a cell comprising the first carrier is activated.

In CA, a multi-carrier nature of a PHY may be exposed to a MAC. In anexample, a HARQ entity may operate on a serving cell. A transport blockmay be generated per assignment/grant per serving cell. A transportblock and potential HARQ retransmissions of the transport block may bemapped to a serving cell.

In the downlink, a base station may transmit (e.g., unicast, multicast,and/or broadcast) one or more Reference Signals (RSs) to a UE (e.g.,PSS, SSS, CSI-RS, DMRS, and/or PT-RS, as shown in FIG. 5A). In theuplink, the UE may transmit one or more RSs to the base station (e.g.,DMRS, PT-RS, and/or SRS, as shown in FIG. 5B). The PSS and the SSS maybe transmitted by the base station and used by the UE to synchronize theUE to the base station. The PSS and the SSS may be provided in asynchronization signal (SS)/physical broadcast channel (PBCH) block thatincludes the PSS, the SSS, and the PBCH. The base station mayperiodically transmit a burst of SS/PBCH blocks.

FIG. 11A illustrates an example of an SS/PBCH block's structure andlocation. A burst of SS/PBCH blocks may include one or more SS/PBCHblocks (e.g., 4 SS/PBCH blocks, as shown in FIG. 11A). Bursts may betransmitted periodically (e.g., every 2 frames or 20 ms). A burst may berestricted to a half-frame (e.g., a first half-frame having a durationof 5 ms). It will be understood that FIG. 11A is an example, and thatthese parameters (number of SS/PBCH blocks per burst, periodicity ofbursts, position of burst within the frame) may be configured based on,for example: a carrier frequency of a cell in which the SS/PBCH block istransmitted; a numerology or subcarrier spacing of the cell; aconfiguration by the network (e.g., using RRC signaling); or any othersuitable factor. In an example, the UE may assume a subcarrier spacingfor the SS/PBCH block based on the carrier frequency being monitored,unless the radio network configured the UE to assume a differentsubcarrier spacing.

The SS/PBCH block may span one or more OFDM symbols in the time domain(e.g., 4 OFDM symbols, as shown in the example of FIG. 11A) and may spanone or more subcarriers in the frequency domain (e.g., 240 contiguoussubcarriers). The PSS, the SSS, and the PBCH may have a common centerfrequency. The PSS may be transmitted first and may span, for example, 1OFDM symbol and 127 subcarriers. The SSS may be transmitted after thePSS (e.g., two symbols later) and may span 1 OFDM symbol and 127subcarriers. The PBCH may be transmitted after the PSS (e.g., across thenext 3 OFDM symbols) and may span 240 subcarriers.

The location of the SS/PBCH block in the time and frequency domains maynot be known to the UE (e.g., if the UE is searching for the cell). Tofind and select the cell, the UE may monitor a carrier for the PSS. Forexample, the UE may monitor a frequency location within the carrier. Ifthe PSS is not found after a certain duration (e.g., 20 ms), the UE maysearch for the PSS at a different frequency location within the carrier,as indicated by a synchronization raster. If the PSS is found at alocation in the time and frequency domains, the UE may determine, basedon a known structure of the SS/PBCH block, the locations of the SSS andthe PBCH, respectively. The SS/PBCH block may be a cell-defining SSblock (CD-SSB). In an example, a primary cell may be associated with aCD-SSB. The CD-SSB may be located on a synchronization raster. In anexample, a cell selection/search and/or reselection may be based on theCD-SSB.

The SS/PBCH block may be used by the UE to determine one or moreparameters of the cell. For example, the UE may determine a physicalcell identifier (PCI) of the cell based on the sequences of the PSS andthe SSS, respectively. The UE may determine a location of a frameboundary of the cell based on the location of the SS/PBCH block. Forexample, the SS/PBCH block may indicate that it has been transmitted inaccordance with a transmission pattern, wherein a SS/PBCH block in thetransmission pattern is a known distance from the frame boundary.

The PBCH may use a QPSK modulation and may use forward error correction(FEC). The FEC may use polar coding. One or more symbols spanned by thePBCH may carry one or more DMRSs for demodulation of the PBCH. The PBCHmay include an indication of a current system frame number (SFN) of thecell and/or a SS/PBCH block timing index. These parameters mayfacilitate time synchronization of the UE to the base station. The PBCHmay include a master information block (MIB) used to provide the UE withone or more parameters. The MIB may be used by the UE to locateremaining minimum system information (RMSI) associated with the cell.The RMSI may include a System Information Block Type 1 (SIB1). The SIB1may contain information needed by the UE to access the cell. The UE mayuse one or more parameters of the MIB to monitor PDCCH, which may beused to schedule PDSCH. The PDSCH may include the SIB1. The SIB1 may bedecoded using parameters provided in the MIB. The PBCH may indicate anabsence of SIB1. Based on the PBCH indicating the absence of SIB1, theUE may be pointed to a frequency. The UE may search for an SS/PBCH blockat the frequency to which the UE is pointed.

The UE may assume that one or more SS/PBCH blocks transmitted with asame SS/PBCH block index are quasi co-located (QCLed) (e.g., having thesame/similar Doppler spread, Doppler shift, average gain, average delay,and/or spatial Rx parameters). The UE may not assume QCL for SS/PBCHblock transmissions having different SS/PBCH block indices.

SS/PBCH blocks (e.g., those within a half-frame) may be transmitted inspatial directions (e.g., using different beams that span a coveragearea of the cell). In an example, a first SS/PBCH block may betransmitted in a first spatial direction using a first beam, and asecond SS/PBCH block may be transmitted in a second spatial directionusing a second beam.

In an example, within a frequency span of a carrier, a base station maytransmit a plurality of SS/PBCH blocks. In an example, a first PCI of afirst SS/PBCH block of the plurality of SS/PBCH blocks may be differentfrom a second PCI of a second SS/PBCH block of the plurality of SS/PBCHblocks. The PCIs of SS/PBCH blocks transmitted in different frequencylocations may be different or the same.

The CSI-RS may be transmitted by the base station and used by the UE toacquire channel state information (CSI). The base station may configurethe UE with one or more CSI-RSs for channel estimation or any othersuitable purpose. The base station may configure a UE with one or moreof the same/similar CSI-RSs. The UE may measure the one or more CSI-RSs.The UE may estimate a downlink channel state and/or generate a CSIreport based on the measuring of the one or more downlink CSI-RSs. TheUE may provide the CSI report to the base station. The base station mayuse feedback provided by the UE (e.g., the estimated downlink channelstate) to perform link adaptation.

The base station may semi-statically configure the UE with one or moreCSI-RS resource sets. A CSI-RS resource may be associated with alocation in the time and frequency domains and a periodicity. The basestation may selectively activate and/or deactivate a CSI-RS resource.The base station may indicate to the UE that a CSI-RS resource in theCSI-RS resource set is activated and/or deactivated.

The base station may configure the UE to report CSI measurements. Thebase station may configure the UE to provide CSI reports periodically,aperiodically, or semi-persistently. For periodic CSI reporting, the UEmay be configured with a timing and/or periodicity of a plurality of CSIreports. For aperiodic CSI reporting, the base station may request a CSIreport. For example, the base station may command the UE to measure aconfigured CSI-RS resource and provide a CSI report relating to themeasurements. For semi-persistent CSI reporting, the base station mayconfigure the UE to transmit periodically, and selectively activate ordeactivate the periodic reporting. The base station may configure the UEwith a CSI-RS resource set and CSI reports using RRC signaling.

The CSI-RS configuration may comprise one or more parameters indicating,for example, up to 32 antenna ports. The UE may be configured to employthe same OFDM symbols for a downlink CSI-RS and a control resource set(CORESET) when the downlink CSI-RS and CORESET are spatially QCLed andresource elements associated with the downlink CSI-RS are outside of thephysical resource blocks (PRBs) configured for the CORESET. The UE maybe configured to employ the same OFDM symbols for downlink CSI-RS andSS/PBCH blocks when the downlink CSI-RS and SS/PBCH blocks are spatiallyQCLed and resource elements associated with the downlink CSI-RS areoutside of PRBs configured for the SS/PBCH blocks.

Downlink DMRSs may be transmitted by a base station and used by a UE forchannel estimation. For example, the downlink DMRS may be used forcoherent demodulation of one or more downlink physical channels (e.g.,PDSCH). An NR network may support one or more variable and/orconfigurable DMRS patterns for data demodulation. At least one downlinkDMRS configuration may support a front-loaded DMRS pattern. Afront-loaded DMRS may be mapped over one or more OFDM symbols (e.g., oneor two adjacent OFDM symbols). A base station may semi-staticallyconfigure the UE with a number (e.g. a maximum number) of front-loadedDMRS symbols for PDSCH. A DMRS configuration may support one or moreDMRS ports. For example, for single user-MIMO, a DMRS configuration maysupport up to eight orthogonal downlink DMRS ports per UE. Formultiuser-MIMO, a DMRS configuration may support up to 4 orthogonaldownlink DMRS ports per UE. A radio network may support (e.g., at leastfor CP-OFDM) a common DMRS structure for downlink and uplink, wherein aDMRS location, a DMRS pattern, and/or a scrambling sequence may be thesame or different. The base station may transmit a downlink DMRS and acorresponding PDSCH using the same precoding matrix. The UE may use theone or more downlink DMRSs for coherent demodulation/channel estimationof the PDSCH.

In an example, a transmitter (e.g., a base station) may use a precodermatrices for a part of a transmission bandwidth. For example, thetransmitter may use a first precoder matrix for a first bandwidth and asecond precoder matrix for a second bandwidth. The first precoder matrixand the second precoder matrix may be different based on the firstbandwidth being different from the second bandwidth. The UE may assumethat a same precoding matrix is used across a set of PRBs. The set ofPRBs may be denoted as a precoding resource block group (PRG).

A PDSCH may comprise one or more layers. The UE may assume that at leastone symbol with DMRS is present on a layer of the one or more layers ofthe PDSCH. A higher layer may configure up to 3 DMRSs for the PDSCH.

Downlink PT-RS may be transmitted by a base station and used by a UE forphase-noise compensation. Whether a downlink PT-RS is present or not maydepend on an RRC configuration. The presence and/or pattern of thedownlink PT-RS may be configured on a UE-specific basis using acombination of RRC signaling and/or an association with one or moreparameters employed for other purposes (e.g., modulation and codingscheme (MCS)), which may be indicated by DCI. When configured, a dynamicpresence of a downlink PT-RS may be associated with one or more DCIparameters comprising at least MCS. An NR network may support aplurality of PT-RS densities defined in the time and/or frequencydomains. When present, a frequency domain density may be associated withat least one configuration of a scheduled bandwidth. The UE may assume asame precoding for a DMRS port and a PT-RS port. A number of PT-RS portsmay be fewer than a number of DMRS ports in a scheduled resource.Downlink PT-RS may be confined in the scheduled time/frequency durationfor the UE. Downlink PT-RS may be transmitted on symbols to facilitatephase tracking at the receiver.

The UE may transmit an uplink DMRS to a base station for channelestimation. For example, the base station may use the uplink DMRS forcoherent demodulation of one or more uplink physical channels. Forexample, the UE may transmit an uplink DMRS with a PUSCH and/or a PUCCH.The uplink DM-RS may span a range of frequencies that is similar to arange of frequencies associated with the corresponding physical channel.The base station may configure the UE with one or more uplink DMRSconfigurations. At least one DMRS configuration may support afront-loaded DMRS pattern. The front-loaded DMRS may be mapped over oneor more OFDM symbols (e.g., one or two adjacent OFDM symbols). One ormore uplink DMRSs may be configured to transmit at one or more symbolsof a PUSCH and/or a PUCCH. The base station may semi-staticallyconfigure the UE with a number (e.g. maximum number) of front-loadedDMRS symbols for the PUSCH and/or the PUCCH, which the UE may use toschedule a single-symbol DMRS and/or a double-symbol DMRS. An NR networkmay support (e.g., for cyclic prefix orthogonal frequency divisionmultiplexing (CP-OFDM)) a common DMRS structure for downlink and uplink,wherein a DMRS location, a DMRS pattern, and/or a scrambling sequencefor the DMRS may be the same or different.

A PUSCH may comprise one or more layers, and the UE may transmit atleast one symbol with DMRS present on a layer of the one or more layersof the PUSCH. In an example, a higher layer may configure up to threeDMRSs for the PUSCH.

Uplink PT-RS (which may be used by a base station for phase trackingand/or phase-noise compensation) may or may not be present depending onan RRC configuration of the UE. The presence and/or pattern of uplinkPT-RS may be configured on a UE-specific basis by a combination of RRCsignaling and/or one or more parameters employed for other purposes(e.g., Modulation and Coding Scheme (MCS)), which may be indicated byDCI. When configured, a dynamic presence of uplink PT-RS may beassociated with one or more DCI parameters comprising at least MCS. Aradio network may support a plurality of uplink PT-RS densities definedin time/frequency domain. When present, a frequency domain density maybe associated with at least one configuration of a scheduled bandwidth.The UE may assume a same precoding for a DMRS port and a PT-RS port. Anumber of PT-RS ports may be fewer than a number of DMRS ports in ascheduled resource. For example, uplink PT-RS may be confined in thescheduled time/frequency duration for the UE.

SRS may be transmitted by a UE to a base station for channel stateestimation to support uplink channel dependent scheduling and/or linkadaptation. SRS transmitted by the UE may allow a base station toestimate an uplink channel state at one or more frequencies. A schedulerat the base station may employ the estimated uplink channel state toassign one or more resource blocks for an uplink PUSCH transmission fromthe UE. The base station may semi-statically configure the UE with oneor more SRS resource sets. For an SRS resource set, the base station mayconfigure the UE with one or more SRS resources. An SRS resource setapplicability may be configured by a higher layer (e.g., RRC) parameter.For example, when a higher layer parameter indicates beam management, anSRS resource in a SRS resource set of the one or more SRS resource sets(e.g., with the same/similar time domain behavior, periodic, aperiodic,and/or the like) may be transmitted at a time instant (e.g.,simultaneously). The UE may transmit one or more SRS resources in SRSresource sets. An NR network may support aperiodic, periodic and/orsemi-persistent SRS transmissions. The UE may transmit SRS resourcesbased on one or more trigger types, wherein the one or more triggertypes may comprise higher layer signaling (e.g., RRC) and/or one or moreDCI formats. In an example, at least one DCI format may be employed forthe UE to select at least one of one or more configured SRS resourcesets. An SRS trigger type 0 may refer to an SRS triggered based on ahigher layer signaling. An SRS trigger type 1 may refer to an SRStriggered based on one or more DCI formats. In an example, when PUSCHand SRS are transmitted in a same slot, the UE may be configured totransmit SRS after a transmission of a PUSCH and a corresponding uplinkDMRS.

The base station may semi-statically configure the UE with one or moreSRS configuration parameters indicating at least one of following: a SRSresource configuration identifier; a number of SRS ports; time domainbehavior of an SRS resource configuration (e.g., an indication ofperiodic, semi-persistent, or aperiodic SRS); slot, mini-slot, and/orsubframe level periodicity; offset for a periodic and/or an aperiodicSRS resource; a number of OFDM symbols in an SRS resource; a startingOFDM symbol of an SRS resource; an SRS bandwidth; a frequency hoppingbandwidth; a cyclic shift; and/or an SRS sequence ID.

An antenna port is defined such that the channel over which a symbol onthe antenna port is conveyed can be inferred from the channel over whichanother symbol on the same antenna port is conveyed. If a first symboland a second symbol are transmitted on the same antenna port, thereceiver may infer the channel (e.g., fading gain, multipath delay,and/or the like) for conveying the second symbol on the antenna port,from the channel for conveying the first symbol on the antenna port. Afirst antenna port and a second antenna port may be referred to as quasico-located (QCLed) if one or more large-scale properties of the channelover which a first symbol on the first antenna port is conveyed may beinferred from the channel over which a second symbol on a second antennaport is conveyed. The one or more large-scale properties may comprise atleast one of: a delay spread; a Doppler spread; a Doppler shift; anaverage gain; an average delay; and/or spatial Receiving (Rx)parameters.

Channels that use beamforming require beam management. Beam managementmay comprise beam measurement, beam selection, and beam indication. Abeam may be associated with one or more reference signals. For example,a beam may be identified by one or more beamformed reference signals.The UE may perform downlink beam measurement based on downlink referencesignals (e.g., a channel state information reference signal (CSI-RS))and generate a beam measurement report. The UE may perform the downlinkbeam measurement procedure after an RRC connection is set up with a basestation.

FIG. 11B illustrates an example of channel state information referencesignals (CSI-RSs) that are mapped in the time and frequency domains. Asquare shown in FIG. 11B may span a resource block (RB) within abandwidth of a cell. A base station may transmit one or more RRCmessages comprising CSI-RS resource configuration parameters indicatingone or more CSI-RSs. One or more of the following parameters may beconfigured by higher layer signaling (e.g., RRC and/or MAC signaling)for a CSI-RS resource configuration: a CSI-RS resource configurationidentity, a number of CSI-RS ports, a CSI-RS configuration (e.g., symboland resource element (RE) locations in a subframe), a CSI-RS subframeconfiguration (e.g., subframe location, offset, and periodicity in aradio frame), a CSI-RS power parameter, a CSI-RS sequence parameter, acode division multiplexing (CDM) type parameter, a frequency density, atransmission comb, quasi co-location (QCL) parameters (e.g.,QCL-scramblingidentity, crs-portscount, mbsfn-subframeconfiglist,csi-rs-configZPid, qcl-csi-rs-configNZPid), and/or other radio resourceparameters.

The three beams illustrated in FIG. 11B may be configured for a UE in aUE-specific configuration. Three beams are illustrated in FIG. 11B (beam#1, beam #2, and beam #3), more or fewer beams may be configured. Beam#1 may be allocated with CSI-RS 1101 that may be transmitted in one ormore subcarriers in an RB of a first symbol. Beam #2 may be allocatedwith CSI-RS 1102 that may be transmitted in one or more subcarriers inan RB of a second symbol. Beam #3 may be allocated with CSI-RS 1103 thatmay be transmitted in one or more subcarriers in an RB of a thirdsymbol. By using frequency division multiplexing (FDM), a base stationmay use other subcarriers in a same RB (for example, those that are notused to transmit CSI-RS 1101) to transmit another CSI-RS associated witha beam for another UE. By using time domain multiplexing (TDM), beamsused for the UE may be configured such that beams for the UE use symbolsfrom beams of other UEs.

CSI-RSs such as those illustrated in FIG. 11B (e.g., CSI-RS 1101, 1102,1103) may be transmitted by the base station and used by the UE for oneor more measurements. For example, the UE may measure a reference signalreceived power (RSRP) of configured CSI-RS resources. The base stationmay configure the UE with a reporting configuration and the UE mayreport the RSRP measurements to a network (for example, via one or morebase stations) based on the reporting configuration. In an example, thebase station may determine, based on the reported measurement results,one or more transmission configuration indication (TCI) statescomprising a number of reference signals. In an example, the basestation may indicate one or more TCI states to the UE (e.g., via RRCsignaling, a MAC CE, and/or a DCI). The UE may receive a downlinktransmission with a receive (Rx) beam determined based on the one ormore TCI states. In an example, the UE may or may not have a capabilityof beam correspondence. If the UE has the capability of beamcorrespondence, the UE may determine a spatial domain filter of atransmit (Tx) beam based on a spatial domain filter of the correspondingRx beam. If the UE does not have the capability of beam correspondence,the UE may perform an uplink beam selection procedure to determine thespatial domain filter of the Tx beam. The UE may perform the uplink beamselection procedure based on one or more sounding reference signal (SRS)resources configured to the UE by the base station. The base station mayselect and indicate uplink beams for the UE based on measurements of theone or more SRS resources transmitted by the UE.

In a beam management procedure, a UE may assess (e.g., measure) achannel quality of one or more beam pair links, a beam pair linkcomprising a transmitting beam transmitted by a base station and areceiving beam received by the UE. Based on the assessment, the UE maytransmit a beam measurement report indicating one or more beam pairquality parameters comprising, e.g., one or more beam identifications(e.g., a beam index, a reference signal index, or the like), RSRP, aprecoding matrix indicator (PMI), a channel quality indicator (CQI),and/or a rank indicator (RI).

FIG. 12A illustrates examples of three downlink beam managementprocedures: P1, P2, and P3. Procedure P1 may enable a UE measurement ontransmit (Tx) beams of a transmission reception point (TRP) (or multipleTRPs), e.g., to support a selection of one or more base station Tx beamsand/or UE Rx beams (shown as ovals in the top row and bottom row,respectively, of P1). Beamforming at a TRP may comprise a Tx beam sweepfor a set of beams (shown, in the top rows of P1 and P2, as ovalsrotated in a counter-clockwise direction indicated by the dashed arrow).Beamforming at a UE may comprise an Rx beam sweep for a set of beams(shown, in the bottom rows of P1 and P3, as ovals rotated in a clockwisedirection indicated by the dashed arrow). Procedure P2 may be used toenable a UE measurement on Tx beams of a TRP (shown, in the top row ofP2, as ovals rotated in a counter-clockwise direction indicated by thedashed arrow). The UE and/or the base station may perform procedure P2using a smaller set of beams than is used in procedure P1, or usingnarrower beams than the beams used in procedure P1. This may be referredto as beam refinement. The UE may perform procedure P3 for Rx beamdetermination by using the same Tx beam at the base station and sweepingan Rx beam at the UE.

FIG. 12B illustrates examples of three uplink beam managementprocedures: U1, U2, and U3. Procedure U1 may be used to enable a basestation to perform a measurement on Tx beams of a UE, e.g., to support aselection of one or more UE Tx beams and/or base station Rx beams (shownas ovals in the top row and bottom row, respectively, of U1).Beamforming at the UE may include, e.g., a Tx beam sweep from a set ofbeams (shown in the bottom rows of U1 and U3 as ovals rotated in aclockwise direction indicated by the dashed arrow). Beamforming at thebase station may include, e.g., an Rx beam sweep from a set of beams(shown, in the top rows of U1 and U2, as ovals rotated in acounter-clockwise direction indicated by the dashed arrow). Procedure U2may be used to enable the base station to adjust its Rx beam when the UEuses a fixed Tx beam. The UE and/or the base station may performprocedure U2 using a smaller set of beams than is used in procedure P1,or using narrower beams than the beams used in procedure P1. This may bereferred to as beam refinement The UE may perform procedure U3 to adjustits Tx beam when the base station uses a fixed Rx beam.

A UE may initiate a beam failure recovery (BFR) procedure based ondetecting a beam failure. The UE may transmit a BFR request (e.g., apreamble, a UCI, an SR, a MAC CE, and/or the like) based on theinitiating of the BFR procedure. The UE may detect the beam failurebased on a determination that a quality of beam pair link(s) of anassociated control channel is unsatisfactory (e.g., having an error ratehigher than an error rate threshold, a received signal power lower thana received signal power threshold, an expiration of a timer, and/or thelike).

The UE may measure a quality of a beam pair link using one or morereference signals (RSs) comprising one or more SS/PBCH blocks, one ormore CSI-RS resources, and/or one or more demodulation reference signals(DMRSs). A quality of the beam pair link may be based on one or more ofa block error rate (BLER), an RSRP value, a signal to interference plusnoise ratio (SINR) value, a reference signal received quality (RSRQ)value, and/or a CSI value measured on RS resources. The base station mayindicate that an RS resource is quasi co-located (QCLed) with one ormore DM-RSs of a channel (e.g., a control channel, a shared datachannel, and/or the like). The RS resource and the one or more DMRSs ofthe channel may be QCLed when the channel characteristics (e.g., Dopplershift, Doppler spread, average delay, delay spread, spatial Rxparameter, fading, and/or the like) from a transmission via the RSresource to the UE are similar or the same as the channelcharacteristics from a transmission via the channel to the UE.

A network (e.g., a gNB and/or an ng-eNB of a network) and/or the UE mayinitiate a random access procedure. A UE in an RRC_IDLE state and/or anRRC_INACTIVE state may initiate the random access procedure to request aconnection setup to a network. The UE may initiate the random accessprocedure from an RRC_CONNECTED state. The UE may initiate the randomaccess procedure to request uplink resources (e.g., for uplinktransmission of an SR when there is no PUCCH resource available) and/oracquire uplink timing (e.g., when uplink synchronization status isnon-synchronized). The UE may initiate the random access procedure torequest one or more system information blocks (SIBs) (e.g., other systeminformation such as SIB2, SIB3, and/or the like). The UE may initiatethe random access procedure for a beam failure recovery request. Anetwork may initiate a random access procedure for a handover and/or forestablishing time alignment for an SCell addition.

FIG. 13A illustrates a four-step contention-based random accessprocedure. Prior to initiation of the procedure, a base station maytransmit a configuration message 1310 to the UE. The procedureillustrated in FIG. 13A comprises transmission of four messages: a Msg 11311, a Msg 2 1312, a Msg 3 1313, and a Msg 4 1314. The Msg 1 1311 mayinclude and/or be referred to as a preamble (or a random accesspreamble). The Msg 2 1312 may include and/or be referred to as a randomaccess response (RAR).

The configuration message 1310 may be transmitted, for example, usingone or more RRC messages. The one or more RRC messages may indicate oneor more random access channel (RACH) parameters to the UE. The one ormore RACH parameters may comprise at least one of following: generalparameters for one or more random access procedures (e.g.,RACH-configGeneral); cell-specific parameters (e.g., RACH-ConfigCommon);and/or dedicated parameters (e.g., RACH-configDedicated). The basestation may broadcast or multicast the one or more RRC messages to oneor more UEs. The one or more RRC messages may be UE-specific (e.g.,dedicated RRC messages transmitted to a UE in an RRC_CONNECTED stateand/or in an RRC_INACTIVE state). The UE may determine, based on the oneor more RACH parameters, a time-frequency resource and/or an uplinktransmit power for transmission of the Msg 1 1311 and/or the Msg 3 1313.Based on the one or more RACH parameters, the UE may determine areception timing and a downlink channel for receiving the Msg 2 1312 andthe Msg 4 1314.

The one or more RACH parameters provided in the configuration message1310 may indicate one or more Physical RACH (PRACH) occasions availablefor transmission of the Msg 1 1311. The one or more PRACH occasions maybe predefined. The one or more RACH parameters may indicate one or moreavailable sets of one or more PRACH occasions (e.g., prach-ConfigIndex).The one or more RACH parameters may indicate an association between (a)one or more PRACH occasions and (b) one or more reference signals. Theone or more RACH parameters may indicate an association between (a) oneor more preambles and (b) one or more reference signals. The one or morereference signals may be SS/PBCH blocks and/or CSI-RSs. For example, theone or more RACH parameters may indicate a number of SS/PBCH blocksmapped to a PRACH occasion and/or a number of preambles mapped to aSS/PBCH blocks.

The one or more RACH parameters provided in the configuration message1310 may be used to determine an uplink transmit power of Msg 1 1311and/or Msg 3 1313. For example, the one or more RACH parameters mayindicate a reference power for a preamble transmission (e.g., a receivedtarget power and/or an initial power of the preamble transmission).There may be one or more power offsets indicated by the one or more RACHparameters. For example, the one or more RACH parameters may indicate: apower ramping step; a power offset between SSB and CSI-RS; a poweroffset between transmissions of the Msg 1 1311 and the Msg 3 1313;and/or a power offset value between preamble groups. The one or moreRACH parameters may indicate one or more thresholds based on which theUE may determine at least one reference signal (e.g., an SSB and/orCSI-RS) and/or an uplink carrier (e.g., a normal uplink (NUL) carrierand/or a supplemental uplink (SUL) carrier).

The Msg 1 1311 may include one or more preamble transmissions (e.g., apreamble transmission and one or more preamble retransmissions). An RRCmessage may be used to configure one or more preamble groups (e.g.,group A and/or group B). A preamble group may comprise one or morepreambles. The UE may determine the preamble group based on a pathlossmeasurement and/or a size of the Msg 3 1313. The UE may measure an RSRPof one or more reference signals (e.g., SSBs and/or CSI-RSs) anddetermine at least one reference signal having an RSRP above an RSRPthreshold (e.g., rsrp-ThresholdSSB and/or rsrp-ThresholdCSI-RS). The UEmay select at least one preamble associated with the one or morereference signals and/or a selected preamble group, for example, if theassociation between the one or more preambles and the at least onereference signal is configured by an RRC message.

The UE may determine the preamble based on the one or more RACHparameters provided in the configuration message 1310. For example, theUE may determine the preamble based on a pathloss measurement, an RSRPmeasurement, and/or a size of the Msg 3 1313. As another example, theone or more RACH parameters may indicate: a preamble format; a maximumnumber of preamble transmissions; and/or one or more thresholds fordetermining one or more preamble groups (e.g., group A and group B). Abase station may use the one or more RACH parameters to configure the UEwith an association between one or more preambles and one or morereference signals (e.g., SSBs and/or CSI-RSs). If the association isconfigured, the UE may determine the preamble to include in Msg 1 1311based on the association. The Msg 1 1311 may be transmitted to the basestation via one or more PRACH occasions. The UE may use one or morereference signals (e.g., SSBs and/or CSI-RSs) for selection of thepreamble and for determining of the PRACH occasion. One or more RACHparameters (e.g., ra-ssb-OccasionMskIndex and/or ra-OccasionList) mayindicate an association between the PRACH occasions and the one or morereference signals.

The UE may perform a preamble retransmission if no response is receivedfollowing a preamble transmission. The UE may increase an uplinktransmit power for the preamble retransmission. The UE may select aninitial preamble transmit power based on a pathloss measurement and/or atarget received preamble power configured by the network. The UE maydetermine to retransmit a preamble and may ramp up the uplink transmitpower. The UE may receive one or more RACH parameters (e.g.,PREAMBLE_POWER_RAMPING_STEP) indicating a ramping step for the preambleretransmission. The ramping step may be an amount of incrementalincrease in uplink transmit power for a retransmission. The UE may rampup the uplink transmit power if the UE determines a reference signal(e.g., SSB and/or CSI-RS) that is the same as a previous preambletransmission. The UE may count a number of preamble transmissions and/orretransmissions (e.g., PREAMBLE_TRANSMISSION_COUNTER). The UE maydetermine that a random access procedure completed unsuccessfully, forexample, if the number of preamble transmissions exceeds a thresholdconfigured by the one or more RACH parameters (e.g., preambleTransMax).

The Msg 2 1312 received by the UE may include an RAR. In some scenarios,the Msg 2 1312 may include multiple RARs corresponding to multiple UEs.The Msg 2 1312 may be received after or in response to the transmittingof the Msg 1 1311. The Msg 2 1312 may be scheduled on the DL-SCH andindicated on a PDCCH using a random access RNTI (RA-RNTI). The Msg 21312 may indicate that the Msg 1 1311 was received by the base station.The Msg 2 1312 may include a time-alignment command that may be used bythe UE to adjust the UE's transmission timing, a scheduling grant fortransmission of the Msg 3 1313, and/or a Temporary Cell RNTI (TC-RNTI).After transmitting a preamble, the UE may start a time window (e.g.,ra-ResponseWindow) to monitor a PDCCH for the Msg 2 1312. The UE maydetermine when to start the time window based on a PRACH occasion thatthe UE uses to transmit the preamble. For example, the UE may start thetime window one or more symbols after a last symbol of the preamble(e.g., at a first PDCCH occasion from an end of a preambletransmission). The one or more symbols may be determined based on anumerology. The PDCCH may be in a common search space (e.g., aType1-PDCCH common search space) configured by an RRC message. The UEmay identify the RAR based on a Radio Network Temporary Identifier(RNTI). RNTIs may be used depending on one or more events initiating therandom access procedure. The UE may use random access RNTI (RA-RNTI).The RA-RNTI may be associated with PRACH occasions in which the UEtransmits a preamble. For example, the UE may determine the RA-RNTIbased on: an OFDM symbol index; a slot index; a frequency domain index;and/or a UL carrier indicator of the PRACH occasions. An example ofRA-RNTI may be as follows:RA-RNTI=1+s_id+14×t_id+14×80×f_id+14×80×8×ul_carrier_idwhere s_id may be an index of a first OFDM symbol of the PRACH occasion(e.g., 0≤s_id<14), t_id may be an index of a first slot of the PRACHoccasion in a system frame (e.g., 0≤t_id<80), f_id may be an index ofthe PRACH occasion in the frequency domain (e.g., 0≤f_id<8), andul_carrier_id may be a UL carrier used for a preamble transmission(e.g., 0 for an NUL carrier, and 1 for an SUL carrier).

The UE may transmit the Msg 3 1313 in response to a successful receptionof the Msg 2 1312 (e.g., using resources identified in the Msg 2 1312).The Msg 3 1313 may be used for contention resolution in, for example,the contention-based random access procedure illustrated in FIG. 13A. Insome scenarios, a plurality of UEs may transmit a same preamble to abase station and the base station may provide an RAR that corresponds toa UE. Collisions may occur if the plurality of UEs interpret the RAR ascorresponding to themselves. Contention resolution (e.g., using the Msg3 1313 and the Msg 4 1314) may be used to increase the likelihood thatthe UE does not incorrectly use an identity of another the UE. Toperform contention resolution, the UE may include a device identifier inthe Msg 3 1313 (e.g., a C-RNTI if assigned, a TC RNTI included in theMsg 2 1312, and/or any other suitable identifier).

The Msg 4 1314 may be received after or in response to the transmittingof the Msg 3 1313. If a C-RNTI was included in the Msg 3 1313, the basestation will address the UE on the PDCCH using the C-RNTI. If the UE'sunique C-RNTI is detected on the PDCCH, the random access procedure isdetermined to be successfully completed. If a TC-RNTI is included in theMsg 3 1313 (e.g., if the UE is in an RRC_IDLE state or not otherwiseconnected to the base station), Msg 4 1314 will be received using aDL-SCH associated with the TC-RNTI. If a MAC PDU is successfully decodedand a MAC PDU comprises the UE contention resolution identity MAC CEthat matches or otherwise corresponds with the CCCH SDU sent (e.g.,transmitted) in Msg 3 1313, the UE may determine that the contentionresolution is successful and/or the UE may determine that the randomaccess procedure is successfully completed.

The UE may be configured with a supplementary uplink (SUL) carrier and anormal uplink (NUL) carrier. An initial access (e.g., random accessprocedure) may be supported in an uplink carrier. For example, a basestation may configure the UE with two separate RACH configurations: onefor an SUL carrier and the other for an NUL carrier. For random accessin a cell configured with an SUL carrier, the network may indicate whichcarrier to use (NUL or SUL). The UE may determine the SUL carrier, forexample, if a measured quality of one or more reference signals is lowerthan a broadcast threshold. Uplink transmissions of the random accessprocedure (e.g., the Msg 1 1311 and/or the Msg 3 1313) may remain on theselected carrier. The UE may switch an uplink carrier during the randomaccess procedure (e.g., between the Msg 1 1311 and the Msg 3 1313) inone or more cases. For example, the UE may determine and/or switch anuplink carrier for the Msg 1 1311 and/or the Msg 3 1313 based on achannel clear assessment (e.g., a listen-before-talk).

FIG. 13B illustrates a two-step contention-free random access procedure.Similar to the four-step contention-based random access procedureillustrated in FIG. 13A, a base station may, prior to initiation of theprocedure, transmit a configuration message 1320 to the UE. Theconfiguration message 1320 may be analogous in some respects to theconfiguration message 1310. The procedure illustrated in FIG. 13Bcomprises transmission of two messages: a Msg 1 1321 and a Msg 2 1322.The Msg 1 1321 and the Msg 2 1322 may be analogous in some respects tothe Msg 1 1311 and a Msg 2 1312 illustrated in FIG. 13A, respectively.As will be understood from FIGS. 13A and 13B, the contention-free randomaccess procedure may not include messages analogous to the Msg 3 1313and/or the Msg 4 1314.

The contention-free random access procedure illustrated in FIG. 13B maybe initiated for a beam failure recovery, other SI request, SCelladdition, and/or handover. For example, a base station may indicate orassign to the UE the preamble to be used for the Msg 1 1321. The UE mayreceive, from the base station via PDCCH and/or RRC, an indication of apreamble (e.g., ra-PreambleIndex).

After transmitting a preamble, the UE may start a time window (e.g.,ra-ResponseWindow) to monitor a PDCCH for the RAR. In the event of abeam failure recovery request, the base station may configure the UEwith a separate time window and/or a separate PDCCH in a search spaceindicated by an RRC message (e.g., recoverySearchSpaceId). The UE maymonitor for a PDCCH transmission addressed to a Cell RNTI (C-RNTI) onthe search space. In the contention-free random access procedureillustrated in FIG. 13B, the UE may determine that a random accessprocedure successfully completes after or in response to transmission ofMsg 1 1321 and reception of a corresponding Msg 2 1322. The UE maydetermine that a random access procedure successfully completes, forexample, if a PDCCH transmission is addressed to a C-RNTI. The UE maydetermine that a random access procedure successfully completes, forexample, if the UE receives an RAR comprising a preamble identifiercorresponding to a preamble transmitted by the UE and/or the RARcomprises a MAC sub-PDU with the preamble identifier. The UE maydetermine the response as an indication of an acknowledgement for an SIrequest.

FIG. 13C illustrates another two-step random access procedure. Similarto the random access procedures illustrated in FIGS. 13A and 13B, a basestation may, prior to initiation of the procedure, transmit aconfiguration message 1330 to the UE. The configuration message 1330 maybe analogous in some respects to the configuration message 1310 and/orthe configuration message 1320. The procedure illustrated in FIG. 13Ccomprises transmission of two messages: a Msg A 1331 and a Msg B 1332.

Msg A 1331 may be transmitted in an uplink transmission by the UE. Msg A1331 may comprise one or more transmissions of a preamble 1341 and/orone or more transmissions of a transport block 1342. The transport block1342 may comprise contents that are similar and/or equivalent to thecontents of the Msg 3 1313 illustrated in FIG. 13A. The transport block1342 may comprise UCI (e.g., an SR, a HARQ ACK/NACK, and/or the like).The UE may receive the Msg B 1332 after or in response to transmittingthe Msg A 1331. The Msg B 1332 may comprise contents that are similarand/or equivalent to the contents of the Msg 2 1312 (e.g., an RAR)illustrated in FIGS. 13A and 13B and/or the Msg 4 1314 illustrated inFIG. 13A.

The UE may initiate the two-step random access procedure in FIG. 13C forlicensed spectrum and/or unlicensed spectrum. The UE may determine,based on one or more factors, whether to initiate the two-step randomaccess procedure. The one or more factors may be: a radio accesstechnology in use (e.g., LTE, NR, and/or the like); whether the UE hasvalid TA or not; a cell size; the UE's RRC state; a type of spectrum(e.g., licensed vs. unlicensed); and/or any other suitable factors.

The UE may determine, based on two-step RACH parameters included in theconfiguration message 1330, a radio resource and/or an uplink transmitpower for the preamble 1341 and/or the transport block 1342 included inthe Msg A 1331. The RACH parameters may indicate a modulation and codingschemes (MCS), a time-frequency resource, and/or a power control for thepreamble 1341 and/or the transport block 1342. A time-frequency resourcefor transmission of the preamble 1341 (e.g., a PRACH) and atime-frequency resource for transmission of the transport block 1342(e.g., a PUSCH) may be multiplexed using FDM, TDM, and/or CDM. The RACHparameters may enable the UE to determine a reception timing and adownlink channel for monitoring for and/or receiving Msg B 1332.

The transport block 1342 may comprise data (e.g., delay-sensitive data),an identifier of the UE, security information, and/or device information(e.g., an International Mobile Subscriber Identity (IMSI)). The basestation may transmit the Msg B 1332 as a response to the Msg A 1331. TheMsg B 1332 may comprise at least one of following: a preambleidentifier; a timing advance command; a power control command; an uplinkgrant (e.g., a radio resource assignment and/or an MCS); a UE identifierfor contention resolution; and/or an RNTI (e.g., a C-RNTI or a TC-RNTI).The UE may determine that the two-step random access procedure issuccessfully completed if: a preamble identifier in the Msg B 1332 ismatched to a preamble transmitted by the UE; and/or the identifier ofthe UE in Msg B 1332 is matched to the identifier of the UE in the Msg A1331 (e.g., the transport block 1342).

A UE and a base station may exchange control signaling. The controlsignaling may be referred to as L1/L2 control signaling and mayoriginate from the PHY layer (e.g., layer 1) and/or the MAC layer (e.g.,layer 2). The control signaling may comprise downlink control signalingtransmitted from the base station to the UE and/or uplink controlsignaling transmitted from the UE to the base station.

The downlink control signaling may comprise: a downlink schedulingassignment; an uplink scheduling grant indicating uplink radio resourcesand/or a transport format; a slot format information; a preemptionindication; a power control command; and/or any other suitablesignaling. The UE may receive the downlink control signaling in apayload transmitted by the base station on a physical downlink controlchannel (PDCCH). The payload transmitted on the PDCCH may be referred toas downlink control information (DCI). In some scenarios, the PDCCH maybe a group common PDCCH (GC-PDCCH) that is common to a group of UEs.

A base station may attach one or more cyclic redundancy check (CRC)parity bits to a DCI in order to facilitate detection of transmissionerrors. When the DCI is intended for a UE (or a group of the UEs), thebase station may scramble the CRC parity bits with an identifier of theUE (or an identifier of the group of the UEs). Scrambling the CRC paritybits with the identifier may comprise Modulo-2 addition (or an exclusiveOR operation) of the identifier value and the CRC parity bits. Theidentifier may comprise a 16-bit value of a radio network temporaryidentifier (RNTI).

DCIs may be used for different purposes. A purpose may be indicated bythe type of RNTI used to scramble the CRC parity bits. For example, aDCI having CRC parity bits scrambled with a paging RNTI (P-RNTI) mayindicate paging information and/or a system information changenotification. The P-RNTI may be predefined as “FFFE” in hexadecimal. ADCI having CRC parity bits scrambled with a system information RNTI(SI-RNTI) may indicate a broadcast transmission of the systeminformation. The SI-RNTI may be predefined as “FFFF” in hexadecimal. ADCI having CRC parity bits scrambled with a random access RNTI (RA-RNTI)may indicate a random access response (RAR). A DCI having CRC paritybits scrambled with a cell RNTI (C-RNTI) may indicate a dynamicallyscheduled unicast transmission and/or a triggering of PDCCH-orderedrandom access. A DCI having CRC parity bits scrambled with a temporarycell RNTI (TC-RNTI) may indicate a contention resolution (e.g., a Msg 3analogous to the Msg 3 1313 illustrated in FIG. 13A). Other RNTIsconfigured to the UE by a base station may comprise a ConfiguredScheduling RNTI (CS-RNTI), a Transmit Power Control-PUCCH RNTI(TPC-PUCCH-RNTI), a Transmit Power Control-PUSCH RNTI (TPC-PUSCH-RNTI),a Transmit Power Control-SRS RNTI (TPC-SRS-RNTI), an Interruption RNTI(INT-RNTI), a Slot Format Indication RNTI (SFI-RNTI), a Semi-PersistentCSI RNTI (SP-CSI-RNTI), a Modulation and Coding Scheme Cell RNTI(MCS-C-RNTI), and/or the like.

Depending on the purpose and/or content of a DCI, the base station maytransmit the DCIs with one or more DCI formats. For example, DCI format00 may be used for scheduling of PUSCH in a cell. DCI format 00 may be afallback DCI format (e.g., with compact DCI payloads). DCI format 01 maybe used for scheduling of PUSCH in a cell (e.g., with more DCI payloadsthan DCI format 0_0). DCI format 1_0 may be used for scheduling of PDSCHin a cell. DCI format 1_0 may be a fallback DCI format (e.g., withcompact DCI payloads). DCI format 1_1 may be used for scheduling ofPDSCH in a cell (e.g., with more DCI payloads than DCI format 1_0). DCIformat 2_0 may be used for providing a slot format indication to a groupof UEs. DCI format 2_1 may be used for notifying a group of UEs of aphysical resource block and/or OFDM symbol where the UE may assume notransmission is intended to the UE. DCI format 2_2 may be used fortransmission of a transmit power control (TPC) command for PUCCH orPUSCH. DCI format 23 may be used for transmission of a group of TPCcommands for SRS transmissions by one or more UEs. DCI format(s) for newfunctions may be defined in future releases. DCI formats may havedifferent DCI sizes, or may share the same DCI size.

After scrambling a DCI with a RNTI, the base station may process the DCIwith channel coding (e.g., polar coding), rate matching, scramblingand/or QPSK modulation. A base station may map the coded and modulatedDCI on resource elements used and/or configured for a PDCCH. Based on apayload size of the DCI and/or a coverage of the base station, the basestation may transmit the DCI via a PDCCH occupying a number ofcontiguous control channel elements (CCEs). The number of the contiguousCCEs (referred to as aggregation level) may be 1, 2, 4, 8, 16, and/orany other suitable number. A CCE may comprise a number (e.g., 6) ofresource-element groups (REGs). A REG may comprise a resource block inan OFDM symbol. The mapping of the coded and modulated DCI on theresource elements may be based on mapping of CCEs and REGs (e.g.,CCE-to-REG mapping).

FIG. 14A illustrates an example of CORESET configurations for abandwidth part. The base station may transmit a DCI via a PDCCH on oneor more control resource sets (CORESETs). A CORESET may comprise atime-frequency resource in which the UE tries to decode a DCI using oneor more search spaces. The base station may configure a CORESET in thetime-frequency domain. In the example of FIG. 14A, a first CORESET 1401and a second CORESET 1402 occur at the first symbol in a slot. The firstCORESET 1401 overlaps with the second CORESET 1402 in the frequencydomain. A third CORESET 1403 occurs at a third symbol in the slot. Afourth CORESET 1404 occurs at the seventh symbol in the slot. CORESETsmay have a different number of resource blocks in frequency domain.

FIG. 14B illustrates an example of a CCE-to-REG mapping for DCItransmission on a CORESET and PDCCH processing. The CCE-to-REG mappingmay be an interleaved mapping (e.g., for the purpose of providingfrequency diversity) or a non-interleaved mapping (e.g., for thepurposes of facilitating interference coordination and/orfrequency-selective transmission of control channels). The base stationmay perform different or same CCE-to-REG mapping on different CORESETs.A CORESET may be associated with a CCE-to-REG mapping by RRCconfiguration. A CORESET may be configured with an antenna port quasico-location (QCL) parameter. The antenna port QCL parameter may indicateQCL information of a demodulation reference signal (DMRS) for PDCCHreception in the CORESET.

The base station may transmit, to the UE, RRC messages comprisingconfiguration parameters of one or more CORESETs and one or more searchspace sets. The configuration parameters may indicate an associationbetween a search space set and a CORESET. A search space set maycomprise a set of PDCCH candidates formed by CCEs at a given aggregationlevel. The configuration parameters may indicate: a number of PDCCHcandidates to be monitored per aggregation level; a PDCCH monitoringperiodicity and a PDCCH monitoring pattern; one or more DCI formats tobe monitored by the UE; and/or whether a search space set is a commonsearch space set or a UE-specific search space set. A set of CCEs in thecommon search space set may be predefined and known to the UE. A set ofCCEs in the UE-specific search space set may be configured based on theUE's identity (e.g., C-RNTI).

As shown in FIG. 14B, the UE may determine a time-frequency resource fora CORESET based on RRC messages. The UE may determine a CCE-to-REGmapping (e.g., interleaved or non-interleaved, and/or mappingparameters) for the CORESET based on configuration parameters of theCORESET. The UE may determine a number (e.g., at most 10) of searchspace sets configured on the CORESET based on the RRC messages. The UEmay monitor a set of PDCCH candidates according to configurationparameters of a search space set. The UE may monitor a set of PDCCHcandidates in one or more CORESETs for detecting one or more DCIs.Monitoring may comprise decoding one or more PDCCH candidates of the setof the PDCCH candidates according to the monitored DCI formats.Monitoring may comprise decoding a DCI content of one or more PDCCHcandidates with possible (or configured) PDCCH locations, possible (orconfigured) PDCCH formats (e.g., number of CCEs, number of PDCCHcandidates in common search spaces, and/or number of PDCCH candidates inthe UE-specific search spaces) and possible (or configured) DCI formats.The decoding may be referred to as blind decoding. The UE may determinea DCI as valid for the UE, in response to CRC checking (e.g., scrambledbits for CRC parity bits of the DCI matching a RNTI value). The UE mayprocess information contained in the DCI (e.g., a scheduling assignment,an uplink grant, power control, a slot format indication, a downlinkpreemption, and/or the like).

The UE may transmit uplink control signaling (e.g., uplink controlinformation (UCI)) to a base station. The uplink control signaling maycomprise hybrid automatic repeat request (HARQ) acknowledgements forreceived DL-SCH transport blocks. The UE may transmit the HARQacknowledgements after receiving a DL-SCH transport block. Uplinkcontrol signaling may comprise channel state information (CSI)indicating channel quality of a physical downlink channel. The UE maytransmit the CSI to the base station. The base station, based on thereceived CSI, may determine transmission format parameters (e.g.,comprising multi-antenna and beamforming schemes) for a downlinktransmission. Uplink control signaling may comprise scheduling requests(SR). The UE may transmit an SR indicating that uplink data is availablefor transmission to the base station. The UE may transmit a UCI (e.g.,HARQ acknowledgements (HARQ-ACK), CSI report, SR, and the like) via aphysical uplink control channel (PUCCH) or a physical uplink sharedchannel (PUSCH). The UE may transmit the uplink control signaling via aPUCCH using one of several PUCCH formats.

There may be five PUCCH formats and the UE may determine a PUCCH formatbased on a size of the UCI (e.g., a number of uplink symbols of UCItransmission and a number of UCI bits). PUCCH format 0 may have a lengthof one or two OFDM symbols and may include two or fewer bits. The UE maytransmit UCI in a PUCCH resource using PUCCH format 0 if thetransmission is over one or two symbols and the number of HARQ-ACKinformation bits with positive or negative SR (HARQ-ACK/SR bits) is oneor two. PUCCH format 1 may occupy a number between four and fourteenOFDM symbols and may include two or fewer bits. The UE may use PUCCHformat 1 if the transmission is four or more symbols and the number ofHARQ-ACK/SR bits is one or two. PUCCH format 2 may occupy one or twoOFDM symbols and may include more than two bits. The UE may use PUCCHformat 2 if the transmission is over one or two symbols and the numberof UCI bits is two or more. PUCCH format 3 may occupy a number betweenfour and fourteen OFDM symbols and may include more than two bits. TheUE may use PUCCH format 3 if the transmission is four or more symbols,the number of UCI bits is two or more and PUCCH resource does notinclude an orthogonal cover code. PUCCH format 4 may occupy a numberbetween four and fourteen OFDM symbols and may include more than twobits. The UE may use PUCCH format 4 if the transmission is four or moresymbols, the number of UCI bits is two or more and the PUCCH resourceincludes an orthogonal cover code.

The base station may transmit configuration parameters to the UE for aplurality of PUCCH resource sets using, for example, an RRC message. Theplurality of PUCCH resource sets (e.g., up to four sets) may beconfigured on an uplink BWP of a cell. A PUCCH resource set may beconfigured with a PUCCH resource set index, a plurality of PUCCHresources with a PUCCH resource being identified by a PUCCH resourceidentifier (e.g., pucch-Resourceid), and/or a number (e.g. a maximumnumber) of UCI information bits the UE may transmit using one of theplurality of PUCCH resources in the PUCCH resource set. When configuredwith a plurality of PUCCH resource sets, the UE may select one of theplurality of PUCCH resource sets based on a total bit length of the UCIinformation bits (e.g., HARQ-ACK, SR, and/or CSI). If the total bitlength of UCI information bits is two or fewer, the UE may select afirst PUCCH resource set having a PUCCH resource set index equal to “0”.If the total bit length of UCI information bits is greater than two andless than or equal to a first configured value, the UE may select asecond PUCCH resource set having a PUCCH resource set index equal to“1”. If the total bit length of UCI information bits is greater than thefirst configured value and less than or equal to a second configuredvalue, the UE may select a third PUCCH resource set having a PUCCHresource set index equal to “2”. If the total bit length of UCIinformation bits is greater than the second configured value and lessthan or equal to a third value (e.g., 1406), the UE may select a fourthPUCCH resource set having a PUCCH resource set index equal to “3”.

After determining a PUCCH resource set from a plurality of PUCCHresource sets, the UE may determine a PUCCH resource from the PUCCHresource set for UCI (HARQ-ACK, CSI, and/or SR) transmission. The UE maydetermine the PUCCH resource based on a PUCCH resource indicator in aDCI (e.g., with a DCI format 1_0 or DCI for 1_1) received on a PDCCH. Athree-bit PUCCH resource indicator in the DCI may indicate one of eightPUCCH resources in the PUCCH resource set. Based on the PUCCH resourceindicator, the UE may transmit the UCI (HARQ-ACK, CSI and/or SR) using aPUCCH resource indicated by the PUCCH resource indicator in the DCI.

FIG. 15 illustrates an example of a wireless device 1502 incommunication with a base station 1504 in accordance with embodiments ofthe present disclosure. The wireless device 1502 and base station 1504may be part of a mobile communication network, such as the mobilecommunication network 100 illustrated in FIG. 1A, the mobilecommunication network 150 illustrated in FIG. 1B, or any othercommunication network. Only one wireless device 1502 and one basestation 1504 are illustrated in FIG. 15 , but it will be understood thata mobile communication network may include more than one UE and/or morethan one base station, with the same or similar configuration as thoseshown in FIG. 15 .

The base station 1504 may connect the wireless device 1502 to a corenetwork (not shown) through radio communications over the air interface(or radio interface) 1506. The communication direction from the basestation 1504 to the wireless device 1502 over the air interface 1506 isknown as the downlink, and the communication direction from the wirelessdevice 1502 to the base station 1504 over the air interface is known asthe uplink. Downlink transmissions may be separated from uplinktransmissions using FDD, TDD, and/or some combination of the twoduplexing techniques.

In the downlink, data to be sent to the wireless device 1502 from thebase station 1504 may be provided to the processing system 1508 of thebase station 1504. The data may be provided to the processing system1508 by, for example, a core network. In the uplink, data to be sent tothe base station 1504 from the wireless device 1502 may be provided tothe processing system 1518 of the wireless device 1502. The processingsystem 1508 and the processing system 1518 may implement layer 3 andlayer 2 OSI functionality to process the data for transmission. Layer 2may include an SDAP layer, a PDCP layer, an RLC layer, and a MAC layer,for example, with respect to FIG. 2A, FIG. 2B, FIG. 3 , and FIG. 4A.Layer 3 may include an RRC layer as with respect to FIG. 2B.

After being processed by processing system 1508, the data to be sent tothe wireless device 1502 may be provided to a transmission processingsystem 1510 of base station 1504. Similarly, after being processed bythe processing system 1518, the data to be sent to base station 1504 maybe provided to a transmission processing system 1520 of the wirelessdevice 1502. The transmission processing system 1510 and thetransmission processing system 1520 may implement layer 1 OSIfunctionality. Layer 1 may include a PHY layer with respect to FIG. 2A,FIG. 2B, FIG. 3 , and FIG. 4A. For transmit processing, the PHY layermay perform, for example, forward error correction coding of transportchannels, interleaving, rate matching, mapping of transport channels tophysical channels, modulation of physical channel, multiple-inputmultiple-output (MIMO) or multi-antenna processing, and/or the like.

At the base station 1504, a reception processing system 1512 may receivethe uplink transmission from the wireless device 1502. At the wirelessdevice 1502, a reception processing system 1522 may receive the downlinktransmission from base station 1504. The reception processing system1512 and the reception processing system 1522 may implement layer 1 OSIfunctionality. Layer 1 may include a PHY layer with respect to FIG. 2A,FIG. 2B, FIG. 3 , and FIG. 4A. For receive processing, the PHY layer mayperform, for example, error detection, forward error correctiondecoding, deinterleaving, demapping of transport channels to physicalchannels, demodulation of physical channels, MIMO or multi-antennaprocessing, and/or the like.

As shown in FIG. 15 , a wireless device 1502 and the base station 1504may include multiple antennas. The multiple antennas may be used toperform one or more MIMO or multi-antenna techniques, such as spatialmultiplexing (e.g., single-user MIMO or multi-user MIMO),transmit/receive diversity, and/or beamforming. In other examples, thewireless device 1502 and/or the base station 1504 may have a singleantenna.

The processing system 1508 and the processing system 1518 may beassociated with a memory 1514 and a memory 1524, respectively. Memory1514 and memory 1524 (e.g., one or more non-transitory computer readablemediums) may store computer program instructions or code that may beexecuted by the processing system 1508 and/or the processing system 1518to carry out one or more of the functionalities discussed in the presentapplication. Although not shown in FIG. 15 , the transmission processingsystem 1510, the transmission processing system 1520, the receptionprocessing system 1512, and/or the reception processing system 1522 maybe coupled to a memory (e.g., one or more non-transitory computerreadable mediums) storing computer program instructions or code that maybe executed to carry out one or more of their respectivefunctionalities.

The processing system 1508 and/or the processing system 1518 maycomprise one or more controllers and/or one or more processors. The oneor more controllers and/or one or more processors may comprise, forexample, a general-purpose processor, a digital signal processor (DSP),a microcontroller, an application specific integrated circuit (ASIC), afield programmable gate array (FPGA) and/or other programmable logicdevice, discrete gate and/or transistor logic, discrete hardwarecomponents, an on-board unit, or any combination thereof. The processingsystem 1508 and/or the processing system 1518 may perform at least oneof signal coding/processing, data processing, power control,input/output processing, and/or any other functionality that may enablethe wireless device 1502 and the base station 1504 to operate in awireless environment.

The processing system 1508 and/or the processing system 1518 may beconnected to one or more peripherals 1516 and one or more peripherals1526, respectively. The one or more peripherals 1516 and the one or moreperipherals 1526 may include software and/or hardware that providefeatures and/or functionalities, for example, a speaker, a microphone, akeypad, a display, a touchpad, a power source, a satellite transceiver,a universal serial bus (USB) port, a hands-free headset, a frequencymodulated (FM) radio unit, a media player, an Internet browser, anelectronic control unit (e.g., for a motor vehicle), and/or one or moresensors (e.g., an accelerometer, a gyroscope, a temperature sensor, aradar sensor, a lidar sensor, an ultrasonic sensor, a light sensor, acamera, and/or the like). The processing system 1508 and/or theprocessing system 1518 may receive user input data from and/or provideuser output data to the one or more peripherals 1516 and/or the one ormore peripherals 1526. The processing system 1518 in the wireless device1502 may receive power from a power source and/or may be configured todistribute the power to the other components in the wireless device1502. The power source may comprise one or more sources of power, forexample, a battery, a solar cell, a fuel cell, or any combinationthereof. The processing system 1508 and/or the processing system 1518may be connected to a GPS chipset 1517 and a GPS chipset 1527,respectively. The GPS chipset 1517 and the GPS chipset 1527 may beconfigured to provide geographic location information of the wirelessdevice 1502 and the base station 1504, respectively.

FIG. 16A illustrates an example structure for uplink transmission. Abaseband signal representing a physical uplink shared channel mayperform one or more functions. The one or more functions may comprise atleast one of: scrambling; modulation of scrambled bits to generatecomplex-valued symbols; mapping of the complex-valued modulation symbolsonto one or several transmission layers; transform precoding to generatecomplex-valued symbols; precoding of the complex-valued symbols; mappingof precoded complex-valued symbols to resource elements; generation ofcomplex-valued time-domain Single Carrier-Frequency Division MultipleAccess (SC-FDMA) or CP-OFDM signal for an antenna port; and/or the like.In an example, when transform precoding is enabled, a SC-FDMA signal foruplink transmission may be generated. In an example, when transformprecoding is not enabled, an CP-OFDM signal for uplink transmission maybe generated by FIG. 16A. These functions are illustrated as examplesand it is anticipated that other mechanisms may be implemented invarious embodiments.

FIG. 16B illustrates an example structure for modulation andup-conversion of a baseband signal to a carrier frequency. The basebandsignal may be a complex-valued SC-FDMA or CP-OFDM baseband signal for anantenna port and/or a complex-valued Physical Random Access Channel(PRACH) baseband signal. Filtering may be employed prior totransmission.

FIG. 16C illustrates an example structure for downlink transmissions. Abaseband signal representing a physical downlink channel may perform oneor more functions. The one or more functions may comprise: scrambling ofcoded bits in a codeword to be transmitted on a physical channel;modulation of scrambled bits to generate complex-valued modulationsymbols; mapping of the complex-valued modulation symbols onto one orseveral transmission layers; precoding of the complex-valued modulationsymbols on a layer for transmission on the antenna ports; mapping ofcomplex-valued modulation symbols for an antenna port to resourceelements; generation of complex-valued time-domain OFDM signal for anantenna port; and/or the like. These functions are illustrated asexamples and it is anticipated that other mechanisms may be implementedin various embodiments.

FIG. 16D illustrates another example structure for modulation andup-conversion of a baseband signal to a carrier frequency. The basebandsignal may be a complex-valued OFDM baseband signal for an antenna port.Filtering may be employed prior to transmission.

A wireless device may receive from a base station one or more messages(e.g. RRC messages) comprising configuration parameters of a pluralityof cells (e.g. primary cell, secondary cell). The wireless device maycommunicate with at least one base station (e.g. two or more basestations in dual-connectivity) via the plurality of cells. The one ormore messages (e.g. as a part of the configuration parameters) maycomprise parameters of physical, MAC, RLC, PCDP, SDAP, RRC layers forconfiguring the wireless device. For example, the configurationparameters may comprise parameters for configuring physical and MAClayer channels, bearers, etc. For example, the configuration parametersmay comprise parameters indicating values of timers for physical, MAC,RLC, PCDP, SDAP, RRC layers, and/or communication channels.

A timer may begin running once it is started and continue running untilit is stopped or until it expires. A timer may be started if it is notrunning or restarted if it is running. A timer may be associated with avalue (e.g. the timer may be started or restarted from a value or may bestarted from zero and expire once it reaches the value). The duration ofa timer may not be updated until the timer is stopped or expires (e.g.,due to BWP switching). A timer may be used to measure a timeperiod/window for a process. When the specification refers to animplementation and procedure related to one or more timers, it will beunderstood that there are multiple ways to implement the one or moretimers. For example, it will be understood that one or more of themultiple ways to implement a timer may be used to measure a timeperiod/window for the procedure. For example, a random access responsewindow timer may be used for measuring a window of time for receiving arandom access response. In an example, instead of starting and expiry ofa random access response window timer, the time difference between twotime stamps may be used. When a timer is restarted, a process formeasurement of time window may be restarted. Other exampleimplementations may be provided to restart a measurement of a timewindow.

For a two-step RA procedure, a wireless device may receive, from a basestation, one or more RRC messages comprising two-step RACH configurationparameters 1330. The one or more RRC messages may broadcast (e.g., viasystem information broadcast messages), multicast (e.g., via systeminformation broadcast messages), and/or unicast (e.g., via dedicated RRCmessages and/or lower layer control signal(s) such as PDCCH) to awireless device. The one or more RRC messages may be wirelessdevice-specific messages, e.g., a dedicated RRC message transmitted to awireless device with RRC INACTIVE 604 or RRC CONNECTED 602. The one ormore RRC messages may comprise parameters required for transmitting MsgA 1331. For example, the parameter may indicate at least one offollowing: PRACH resource allocation, preamble format, SSB information(e.g., total number of SSBs, downlink resource allocation of SSBtransmission, transmission power of SSB transmission, uplink radioresources (time-frequency radio resource, DMRS, MCS, etc.) for one ormore transport block transmissions, and/or association between PRACHresource allocation and the uplink radio resources (or associationsbetween the uplink radio resources and downlink reference signals).

In the UL transmission (e.g., Msg A 1331) of a two-step RA procedure, awireless device may transmit, via a cell and to a base station, at leastone Random Access Preamble (RAP) (e.g., Preamble 1341) and/or one ormore transport blocks (e.g., Transport block 1342). For example, the oneor more transport blocks may comprise one of data, security information,device information such as IMSI/TMSI, and/or other information. Forexample, the one or more transport blocks may comprise a wireless deviceidentifier (ID) that may be used for a contention resolution. In the DLtransmission of the two-step RA procedure, a base station may transmitMsg B 1332 (e.g., a random access response corresponding to MsgA 1331)that may comprise at least one of following: a timing advance commandindicating the TA value, a power control command, an UL grant (e.g.,radio resource assignment, and/or MCS), the identifier for contentionresolution, an RNTI (e.g., C-RNTI or TC-RNTI), and/or other information.The Msg B 1332 may comprise a preamble identifier corresponding to thePreamble 1341, a positive or negative acknowledgement of a reception ofthe one or more transport blocks 1342, an implicit and/or explicitindication of a successful decoding of the one or more transport blocks1342, an indication of fallback to a non-two step RA procedure (e.g.,contention-based RA procedure in FIG. 13A or contention-free RAprocedure in FIG. 13B), and/or combination thereof.

A wireless device initiating two step RA procedure may transmit Msg Acomprising at least one preamble and at least one transport block. Theat least one transport block may comprise an identifier that thewireless device uses for a contention resolution. For example, theidentifier is a C-RNTI (e.g., for a wireless device with RRC Connected).The wireless device may indicate the C-RNTI to the base station based ona particular message format that may be predefined. For example, the atleast one transport block comprises an C-RNTI MAC CE (e.g., 16 bitsfields indicate the C-RNTI) with an LCID in a subheader corresponding tothe C-RNTI MAC CE. For example, the LCID may be used for a base stationto identify (detect, parse, and/or decode) the C-RNTI MAC CE from areceived signal or message (e.g., MAC PDU) transmitted from the wirelessdevice. The identifier may be sequence(s) and/or number(s) that thewireless device generates (e.g., for a case that C-RNTI has not beenassigned, by the base station, to the wireless device yet). The wirelessdevice may generate the identifier randomly and/or generate based on asubscriber, device information of the wireless device (e.g., IMSI/TMSI)and/or a resume identifier assigned by the base station to the wirelessdevice. For example, the identifier may be an extended and/or truncatedsubscriber and/or device information of the wireless device (e.g.,IMSI/TMSI). The wireless device may start to monitor a downlink controlchannel for Msg B corresponding to the Msg A, e.g., after or in responseto transmitting the Msg A. A control resource set and/or a search spacefor monitoring the downlink control channel may be indicated and/orconfigured by message(s), e.g., broadcast RRC message and/or wirelessdevice specific RRC message, transmitted by a base station. The Msg Bmay be scrambled by a particular RNTI. The wireless device may use anRNTI (e.g., C-RNTI) already assigned by the base station as theparticular RNTI may be. The wireless device may determine the particularRNTI based on at least one of following: a time resource index (e.g., anindex of a first OFDM symbol of and/or an index of a first slot) ofPRACH occasion that the at least one preamble is transmitted, afrequency resource index of PRACH occasion that the at least onepreamble is transmitted, a time resource index (e.g., an index of afirst OFDM symbol of and/or an index of a first slot) PUSCH occasionthat the at least one transport block is transmitted, a frequencyresource index of PUSCH occasion that the at least one transport blockis transmitted, an indicator (e.g., 0 or 1) of an uplink carrier wherethe Msg A is transmitted. The wireless device may consider (ordetermine) that the two step RA procedure is successfully completedbased on one or more conditions. At least one of the one or moreconditions may be that the Msg B comprises a preamble index (oridentifier) matched to the at least one preamble that the wirelessdevice transmits to the base station. At least one of the one or moreconditions may be that the Msg B comprises and/or indicates a contentionresolution identifier matched to the identifier that the wireless devicetransmits to the base station for the contention resolution. In anexample, the wireless device may receive the Msg B indicating aretransmission of the at least one transport block. For example, the MsgB indicating a retransmission of the at least one transport blockcomprises an UL grant indicating uplink resource(s) used for theretransmission of the at least one transport block.

In the UL transmission of a two-step RA procedure, a wireless device maytransmit, via a cell and to a base station, at least one RAP and one ormore TBs. The wireless device may receive message(s) one or moreconfiguration parameters for the UL transmission of the two-step RAprocedure, e.g., at step 1330 in FIG. 13 . For example, the one or moreconfiguration parameters may indicate at least one of: PRACHoccasion(s), preamble format, a number of transmitting SSBs, downlinkresources of transmissions of SSB(s), transmission power of SSBtransmission(s), association between each of PRACH occasion(s) and eachof SSB(s), PUSCH resource(s) (in terms of time, frequency,code/sequence/signature) for one or more TB transmissions, associationbetween each of PRACH occasion(s) and each of PUSCH resource(s), and/orpower control parameters of one or more TB transmissions. The powercontrol parameters of one or more TB transmissions may comprise at leastone of following: power parameter value(s) for cell and/or UE specificpower adjustments used for determining a received target power, ascaling factor (e.g., inter-cell interference control parameter) of apathloss measurement, reference signal power used for determining apathloss measurement, a power offset with respect to a power of preambletransmission, and/or one or more power offsets. For example, thewireless device measures received signal power(s) (e.g., RSRP) and/orquality (e.g., RSRQ) of one or more SSBs that a base station transmits.The wireless device may select at least one SSB based on the measurementand determine at least one PRACH occasion associated with the at leastone SSB and/or at least one PUSCH resource associated with the at leastone PRACH occasion and/or associated with the at least one SSB (thisassociation may be configured explicitly by the message(s) and/orimplicitly through a first association between the at least one SSB andthe at least one PRACH occasion and a second association between the atleast one PRACH occasion and the at least one PUSCH resource). Thewireless device may transmit at least one RAP via the at least one PRACHoccasion and/or transmit at least one TB via the at least one PUSCHresource. The wireless device may determine transmit powers of the atleast one RAP and/or the at least one TB based on the configurationparameters indicated by the message(s). For example, the configurationparameters indicate uplink transmit power control parameters comprisingat least one of following: a received target power for a base station,one or more power offsets, power ramping step, power ramping counter,retransmission counter, pathloss reference signal index (or indices),pathloss reference signal reference power. At least one of the uplinktransmit power control parameters may be shared between an uplinktransmit power for the at least one RAP and an uplink transmit power forthe at least one TB. For example, sharing the at least one of the uplinktransmit power control parameter may reduce a size of the message(s)(e.g., comparing with a case that the at least one uplink transmit powercontrol parameter repeats for the at least one RAP and for the at leastone TB in the messages(s)). None of the uplink transmit power controlparameters may be shared between an uplink transmit power for the atleast one RAP and an uplink transmit power for the at least one TB. Amessage structure of the message(s) may be flexible such that a basestation indicates to the wireless device whether at least one of (orwhich one or more of) the uplink transmit power control parameters maybe shared between an uplink transmit power for the at least one RAP andan uplink transmit power for the at least one TB. For example, thewireless device determines, based on the message structure of themessage(s), whether at least one of (or which one or more of) the uplinktransmit power control parameters may be shared between an uplinktransmit power for the at least one RAP and an uplink transmit power forthe at least one TB.

There may be one or more ways for a wireless device to generate one ormore candidate preambles that may be used for a two-step RA procedure.For example, a two-step RACH configuration comprises RAP generatingparameter(s) (e.g., a root sequence), based on which the wireless devicegenerates the one or more candidate preambles. The wireless device may(e.g., randomly) select one of the one or more candidate preambles as anRAP to be used for transmission of Preamble 1341. The RAP generatingparameters may be DL reference signal (e.g., SSB or CSI-RS)-specific,cell-specific, and/or wireless device-specific. For example, the RAPgenerating parameters for a first DL reference signal are different fromthe RAP generating parameters for a second DL reference signal. Forexample, the RAP generating parameters are common for one or more DLreference signals of a cell where a wireless device initiates a two-stepRA procedure. For example, a wireless device receives, from a basestation, a control message (e.g., SIB message, RRC message dedicated toa wireless device, and/or a PDCCH order for a secondary cell addition)that indicates one or more preamble indices of one or more RAPs to beused for a two-step RA procedure of the wireless device. The one or morecandidate preambles may be grouped into one or more groups. For example,each group is associated with a specific amount of data fortransmission. For example, the amount of data indicates a size of one ormore transport blocks that a wireless device to transmit and/orindicates a size of uplink data that remains in the buffer. Each of theone or more groups may be associated with a range of data size. Forexample, a first group of the one or more groups comprises RAPsindicating small data transmission(s) of transport block(s) during thetwo-step RA procedure, and a second group may comprise RAPs indicatinglarger data transmission(s) of transport block(s) during the two-step RAprocedure, and so on. A base station may transmit an RRC messagecomprising one or more thresholds based on which a wireless device maydetermine which group of RAPs the wireless device selects an RAP. Forexample, the one or more thresholds indicate one or more data sizes thatdetermine the one or more groups. Based on a size of uplink data that awireless device potentially transmits; the wireless device may comparethe size of uplink data with the one or more data sizes and determine aparticular group from the one or more groups. By transmitting an RAPselected from the specific group, the wireless device may indicate, to abase station, a (e.g., estimated) size of uplink data that the wirelessdevice transmits, to the base station. The indication of the size ofuplink data may be used for a base station to determine a proper size ofuplink radio resources for (re)transmission of the uplink data.

In a two-step RA procedure, a wireless device may transmit an RAP via aPRACH occasion indicated by a two-step RACH configuration. The wirelessdevice may transmit one or more TBs via an UL radio resource (e.g.,PUSCH) indicated by a two-step RACH configuration. A first transmissionof the RAP and a second transmission of the one or more TBs may bescheduled in a TDM (time-division multiplexing) manner, a FDM(frequency-division multiplexing) manner, a CDM (code-divisionmultiplexing) manner, and/or any combination thereof. The firsttransmission of the RAP may be overlapped in time (partially orentirely) with the second transmission of the one or more TBs. Thetwo-step RACH configuration may indicate a portion (e.g., in frequencydomain and/or in time domain) of overlapping of radio resources betweenthe RAP and one or more TB transmissions. The first transmission of theRAP may be TDMed without overlapping with the second transmission of theone or more TBs in different frequencies (e.g., PRBs) or in the samefrequency (e.g., PRB). The two-step RACH configuration may indicate oneor more UL radio resources associated with one or more RAPs (or RAPgroups) and/or the PRACH occasion. For example, each of one or moredownlink reference signals (SSBs or CSI-RSs) is associated with one ormore PRACH occasions and/or one or more RAPs. A wireless device maydetermine at least one PRACH occasion among the one or more PRACHoccasions and/or at least one RAP among the one or more RAPs. Forexample, a wireless device measures RSRP and/or RSRQ of the one or moredownlink reference signals and selects a first downlink reference signalfrom the one or more downlink reference signals. For example, an RSRP ofthe first downlink reference signal is larger than a threshold (e.g.,indicated by a base station via a control message or signal). Thewireless device may select at least one RAP and/or at least one PRACHoccasion, that are associated with the first downlink reference signal,as a radio resource for Preamble 1341. Based on a selection of the atleast one RAP and/or the at least one PRACH occasion, the wirelessdevice may determine at least one UL radio resource (e.g., PUSCHoccasions) where the wireless device transmits one or more TBs as a partof a two-step RACH procedure. The wireless device may determine the atleast one UL radio resource (e.g., PUSCH occasions) based on the firstdownlink reference signal, e.g., if a control message and/or a controlsignal that the wireless device received from the base station indicateassociations between one or more UL radio resources (e.g., PUSCHoccasions) and the one or more downlink reference signals.

The one or more UL radio resources may be indicated based on a framestructure in FIG. 7 , and/or OFDM radio structure in FIG. 8 . Forexample, time domain resource(s) of the one or more UL radio resourcesis indicated with respect to a particular SFN (SFN=0), slot number, anOFDM symbol number, and/or a combination thereof. For example, timedomain resource(s) of the one or more UL radio resources is indicatedwith respect to a subcarrier number, a number of resource elements, anumber of resource blocks, RBG number, frequency index for a frequencydomain radio resource, and/or a combination thereof. For example, theone or more UL radio resources may be indicated based on a time offsetand/or a frequency offset with respect to one or more PRACH occasions ofa selected RAP. The UL transmissions may occur, e.g., in the same slot(or subframe) and/or in a different slot, e.g., in consecutive slots (orsubframes). For example, the one or more UL radio resources (e.g., PUSCHoccasions) may be configured periodically, e.g., a periodic resources ofconfigured grant Type 1 or Type 2.

A PUSCH occasion for two-step RA procedure may be an uplink radioresource for a transport block 1342 (e.g., payload) transmissionassociated with a PRACH preamble in MsgA 1331 of two-step RA procedure.One or more examples of a resource allocation of a PUSCH occasion may be(but not limited to) that PUSCH occasions are separately configured fromPRACH occasions. For example, for a PUSCH occasion may be determinedbased on a periodic resource indicated by a configured grant (e.g.,configured grant Type 1/Type 2 and/or SPS). A wireless device maydetermine the PUSCH occasion further based on an association between thePRACH and PUSCH for msgA transmission. For example, a wireless devicemay receive, from a base station, configuration parameters indication atleast one of following: a modulation and coding scheme, a transportblock size, a number of FDMed PUSCH occasions (the FDMed PUSCH occasionsmay comprise guard band and/or guard period, e.g., if exist, and theFDMed PUSCH occasions under the same Msg A PUSCH configurations may beconsecutive in frequency domain), a number of PRBs per PUSCH occasion, anumber of DMRS symbols/ports/sequences per PUSCH occasion, a number ofrepetitions for Msg A PUSCH (Transport block 1342) transmission, abandwidth of PRB level guard band, duration of guard time, a PUSCHmapping type of Transport block 1342, a periodicity (e.g., MsgA PUSCHconfiguration period), offset(s) (e.g., in terms of any combination ofat least one of symbol, slot, subframe, and/or SFN), a time domainresource allocation (e.g., in a slot for MsgA PUSCH: starting symbol, anumber of symbols per PUSCH occasion, a number of time-domain PUSCHoccasions), a frequency starting point.

One or more examples of a resource allocation of a PUSCH occasion may be(but not limited to) that a base station configure a relative location(e.g., in time and/or frequency) of the PUSCH occasion with respect to aPRACH occasion. For example, time and/or frequency relation betweenPRACH preambles in a PRACH occasion and PUSCH occasions may be a singlespecification fixed value. For example, a time and/or frequency relationbetween each PRACH preamble in a PRACH occasion to the PUSCH occasion isa single specification fixed value. For example, different preambles indifferent PRACH occasions have different values. For example, a timeand/or frequency relation between PRACH preambles in a PRACH occasionand PUSCH occasions are single semi-statically configured value. Forexample, a time and/or frequency relation between each PRACH preamble ina PRACH occasion to the PUSCH occasion is semi-statically configuredvalue. For example, different preambles in different PRACH occasionshave different values. For example, any combination of above example maybe implemented/configured, and the time and frequency relation need notbe the same alternative. For example, a wireless device may receive,from a base station, configuration parameters indication at least one offollowing: a modulation and coding scheme, a transport block size, anumber of FDMed PUSCH occasions (the FDMed PUSCH occasions may compriseguard band and/or guard period, e.g., if exist, and the FDMed PUSCHoccasions under the same Msg A PUSCH configurations may be consecutivein frequency domain), a number of PRBs per PUSCH occasion, a number ofDMRS symbols/ports/sequences per PUSCH occasion, a number of repetitionsfor Msg A PUSCH (Transport block 1342) transmission, a bandwidth of PRBlevel guard band, duration of guard time, a PUSCH mapping type ofTransport block 1342, a time offset (e.g., a combination of slot-leveland symbol-level indication) with respect to a reference point (e.g., aparticular SFN, associated PRACH occasion, and/or start or end ofassociated PRACH slot), a number of symbols per PUSCH occasion, a numberof TDMed PUSCH occasions.

For a two-step RA procedure, a resource allocation for a payloadtransmission in a PUSCH occasion may be predefined and/or configured.For example, a size of a resource in a PUSCH occasion may be predefinedand/or configured. The resource may be continuous or non-continuous(e.g., a base station may flexibly configure the resource). The resourcemay be partitioned into a plurality of resource groups. For example, asize of each of resource groups within a PUSCH occasion may be the sameor different (e.g., depending on the configuration of the two-step RAprocedure). Each resource group index may be mapped to one or morepreamble index.

For example, a base station may configure a wireless device with one ormore parameters indicating a starting point of time and/re frequency fora PUSCH occasion, a number of resource groups, and a size of each of theresource groups. An index of each of the resource groups may be mappedto a preamble index (e.g., a particular preamble) and/or a particularPPRACH occasion. The wireless device may determine a location of each ofresource groups at least based on a preamble index (e.g., in case RO andPUSCH occasion are 1-to-1 mapping) and/or based on an RO index and apreamble index (e.g., in the case of multiple ROs are associated withone PUSCH occasion).

A wireless device may receive, from a base station, configurationparameters indicating the starting point of time/frequency for the PUSCHoccasion and/or a set of continuous basic unit of PUSCH resources. Thesize of resource unit may be identical, and the total available numberof basic unit may be pre-configured. A wireless device may use one ormultiple resource unit for the MsgA 1331 transmission, depending on thepayload size. The starting resource unit index may be mapped to preambleindex, and the length of occupied PUSCH resource (as the number ofresource unit) may be either mapped to preamble index or explicitlyindicated (e.g. in UCI).

A number of resource groups and/or the detailed mapping amongpreamble(s), resource group(s), and DMRS port(s) may be pre-definedand/or semi-statically configured (and/or indicated by DCI dynamically),e.g., to avoid a blind detection from a base station when multiplepreambles are mapped to the same resource group.

For a payload transmission via a PUSCHC occasion in a two-step RAprocedure, a wireless device may receive, from a base station,configuration parameters indicating one or more MCSs and one or moreresource sizes for a transmission of payload. The MCS and resource sizemay be related to a size of the payload. For example, the configurationparameters received by the wireless device may indicate one or morecombinations (and/or associations) of a size of the payload, MCS, andresource size. For example, one or more particular modulation types(e.g., pi/2-BPSK, BPSK, QPSK) may be associated with a small size ofpayload. For example, a one or more particular modulation types (e.g.,QPSK) may be used for a wireless device with a particular RRC state(e.g., RRC IDLE and/or RRC INACTIVE). For example, the configurationparameters received by the wireless device may indicate a number of PRBsused for payload transmission over an entire UL BWP and/or over a partof UL BWP (e.g., this may be predefined and/or semi-staticallyconfigured by RRC). The configuration parameters received by thewireless device may indicate one or more repetitions of Transport block1342 (e.g., payload). For example, a number of repetitions ispredefined, semi-statically configured, and/or triggered based on one ormore conditions (e.g., RSRP of downlink reference signals, and/or aparticular RRC state, and/or a type of a wireless device, e.g.,stationary, IoT, etc.) for the coverage enhancement of a transmission ofpayload.

A wireless device may receive, from a base station, one or more two-stepRA configurations for Transport block 1342 (e.g., payload) transmission.The one or more two-step RA configuration may indicate one or morecombinations of payload size, MCS, and/or resource size. The number ofthe one or more two-step RA configurations and one or more parametervalues (e.g., payload size, MCS, and/or resource size) for each of theone or more two-step RA configurations may depend on the content of MsgAand/or an RRC state of a wireless device.

Based on configured two-step RA configuration parameters, a wirelessdevice may transmit MsgA, e.g., comprising at least one preamble via aPRACH occasion and/or a Transport block 1342 (e.g., payload) via a PUSCHoccasion, to a base station. MsgA may comprise an identifier forcontention resolution. For example, a wireless device may construct aMAC header as the msgA payload with a plurality of bits (e.g., 56 and/or72 bits). For example, MsgA may comprise BSR, PHR, RRC messages,connection request, etc. For example, MsgA may comprise UCI. The UCI inMsgA may comprise at least one of following, e.g., if MsgA comprises theUCI: an MCS indication, HARQ-ACK/NACT and/or CSI report. HARQ for MsgAmay combine between an initial transmission of Msg.A and one or moreretransmissions of Msg.A PUSCH. For example, Msg A may indicate atransmission time of MsgA in the PUSCH of MsgA. A size of msgA maydepend on use case.

There may be a case that a wireless device receive, from a base station,configuration parameters indicating different (or independent) PRACHoccasions between two-step RA and four-step RA. The different (orindependent) PRACH occasions may reduce receiver uncertainty and/orreduce the access delay. The base station may configure the wirelessdevice with different (or independent) PRACH resources such that thebase station identifies whether a received preamble is transmitted by awireless device for two-step RA or four-step RA based on PRACH occasionthat the base station receives the received preamble. A base station mayflexibility determine whether to configure shared PRACH occasions orseparate PRACH occasions between two-step RA and four-step RAprocedures. A wireless device may receive, from the base station, RRCmessage(s) and/or DCI indicating an explicit or implicit indication ofwhether to configure shared PRACH occasions or separate PRACH occasionsbetween two-step RA and four-step RA procedures. There may be a casethat a base station configures one or more PRACH occasions sharedbetween two-step RA and four-step RA and preambles partitioned for thetwo-step RA and the four-step RA.

FIG. 17A, FIG. 17B, and FIG. 17C are examples of radio resourceallocations of a PRACH resource and one or more associated UL radioresources based on a time offset, a frequency offset, and a combinationof a time offset and a frequency offset, respectively as per an aspectof an example embodiment of the present disclosure. For example, a PRACHoccasion and one or more associated UL radio resources (e.g., PUSCHoccasions) for MsgA 1331 may be allocated with a time offset and/orfrequency offset, e.g., provided by RRC messages (as a part of RACHconfig.) and/or predefined (e.g., as a mapping table). FIG. 17A is anexample of a PRACH occasion TDMed with a UL radio resources (e.g., PUSCHoccasion) as per an aspect of an example embodiment of the presentdisclosure. FIG. 17B is an example of a PRACH occasion FDMed with a ULradio resources (e.g., PUSCH occasion) as per an aspect of an exampleembodiment of the present disclosure. FIG. 17C is an example of a PRACHoccasion TDMed and FDMed with a UL radio resources (e.g., PUSCHoccasion) as per an aspect of an example embodiment of the presentdisclosure.

A wireless device may receive, from a base station, one or more downlinkreference signals (e.g., SSBs or CSI-RSs), and each of the one or moredownlink reference signals may be associated with one or more RACHresources (e.g., PRACH occasions) and/or one or more UL radio resources(e.g., PUSCH occasions) provided by a two-step RACH configuration. Awireless device may measure one or more downlink reference signals and,based on measured received signal strength and/or quality (or based onother selection rule), may select at least one downlink referencesignals among the one or more downlink reference signals. The wirelessdevice may respectively transmit an RAP (e.g., Preamble 1341) and one ormore TBs (e.g., Transport block 1342) via a PRACH occasion associatedwith the at least one downlink reference signal, and via UL radioresources (e.g., a PUSCH occasions) associated with the PRACH occasionand/or associated with the at least one downlink reference signal.

In an example, a base station may employ an RAP receive from a wirelessdevice to adjust UL transmission timing of one or more TBs for thewireless device in a cell and/or to aid in UL channel estimation for oneor more TBs. A portion of the UL transmission for one or more TBs in atwo-step RACH procedure may comprise, e.g., a wireless device ID, aC-RNTI, a service request such as buffer state reporting (e.g., a bufferstatus report) (BSR), one or more user data packets, and/or otherinformation. A wireless device, e.g., in an RRC CONNECTED 602 state, mayuse a C-RNTI as an identifier of the wireless device (e.g., a wirelessdevice ID). A wireless device, e.g., in an RRC INACTIVE 604 state, mayuse a C-RNTI (if available), a resume ID, or a short MAC-ID as anidentifier of the wireless device. A wireless device, e.g., in an RRCIDLE 606 state, may use a C-RNTI (if available), a resume ID, a shortMAC-ID, an IMSI (International Mobile Subscriber Identifier), a T-IMSI(Temporary-IMSI), and/or a random number (e.g., generated by thewireless device) as an identifier of the wireless device.

In a two-step RA procedure, a wireless device may receive two separateresponses corresponding to Msg A; a first response for RAP (e.g.,Preamble 1342) transmission; and a second response for a transmission ofone or more TBs (e.g., Transport block 1342). A wireless device maymonitor a PDCCH (e.g., common search space and/or a wireless devicespecific search space) to detect the first response with a random accessRNTI generated based on time and/or frequency indices of PRACH resourcewhere the wireless device transmits an RAP. A wireless device maymonitor a common search space and/or a wireless device specific searchspace to detect the second response. The wireless device may employ asecond RNTI to detect the second response. For example, the second RNTIis a C-RNTI if configured, a random access RNTI generated based on timeand/or frequency indices of PRACH occasion where the wireless devicetransmits an RAP, or an RNTI generated based on time and/or frequencyindices (and/or DM-RS ID) of PUSCH resource(s) where the wireless devicetransmits the or more TBs. The wireless device specific search space maybe predefined and/or configured by an RRC message received from a basestation.

One or more events may trigger a two-step random access procedure. Forexample, one or more events may be at least one of: initial access fromRRC_IDLE, RRC connection re-establishment procedure, handover, DL or ULdata arrival during RRC_CONNECTED 602 when UL synchronization status isnon-synchronized, transition from RRC INACTIVE 604, beam failurerecovery procedure, and/or request for other system information. Forexample, a PDCCH order, an MAC entity of the wireless device, and/or abeam failure indication may initiate a random access procedure.

A wireless device may initiate a two-step RA procedure in a particularcondition, e.g., depending on a service of data to be transmitted (e.g.,delay sensitive data such URLLC) and/or radio conditions. For example, abase station may configure one or more wireless devices with a two-stepRA procedure, for example, if a cell is small (e.g., there is no need ofa TA) and/or for a case of stationary wireless device (e.g., there is noneed of TA update). A wireless device may acquire the configuration, viaone or more RRC messages (e.g., MIB, system information blocks,multicast and/or unicast RRC signaling), and/or via L1 control signaling(e.g., PDCCH order) used to initiate a two-step RA procedure.

For example, in a macro coverage area, a wireless device may have astored and/or persisted TA value, e.g., a stationary or near stationarywireless device such as a sensor-type wireless device. In this case atwo-step RA procedure may be initiated. A base station having macrocoverage may use broadcasting and/or dedicated signaling to configure atwo-step RA procedure with one or more wireless devices having storedand/or persisted TA value(s) under the coverage.

A wireless device in an RRC CONNECTED 602 state may perform a two-stepRA procedure. For example, the two-step RA procedure may be initiatedwhen a wireless device performs a handover (e.g., network-initiatedhandover), and/or when the wireless device requires or requests a ULgrant for a transmission of delay-sensitive data and there are nophysical-layer uplink control channel resources available to transmit ascheduling request. A wireless device in an RRC INACTIVE 604 state mayperform a two-step RA procedure, e.g., for a small data transmissionwhile remaining in the RRC INACTIVE 604 state or for resuming aconnection. A wireless device may initiate a two-step RA procedure, forexample, for initial access such as establishing a radio link,re-establishment of a radio link, handover, establishment of ULsynchronization, and/or a scheduling request when there is no UL grant.

The following description presents one or more examples of an RAprocedure. The procedures and/or parameters described in the followingmay not be limited to a specific type of an RA procedure. The proceduresand/or parameters described in the following may be applied for afour-step RA procedure and/or a two-step RA procedure. For example, anRA procedure may refer to a four-step RA procedure and/or a two-step RAprocedure in the following description.

A wireless device may perform a cell search. For example, the wirelessdevice may acquire time and frequency synchronization with the cell anddetect a first physical layer cell ID of the cell during the cell searchprocedure. The wireless device may perform the cell search, for example,when the wireless device has received one or more synchronizationsignals (SS), for example, the primary synchronization signal (PSS) andthe secondary synchronization signal (SSS). The wireless device mayassume that reception occasions of one or more physical broadcastchannels (PBCH), PSS, and SSS are in consecutive symbols, and, forexample, form a SS/PBCH block (SSB). For example, the wireless devicemay assume that SSS, PBCH demodulation reference signal (DM-RS), andPBCH data have the same energy per resource element (EPRE). For example,the wireless device may assume that the ratio of PSS EPRE to SSS EPRE ina SS/PBCH block is a particular value (e.g., either 0 dB or 3 dB). Forexample, the wireless device may determine that the ratio of PDCCH DM-RSEPRE to SSS EPRE is within a particular range (e.g., from −8 dB to 8dB), for example, when the wireless device has not been provideddedicated higher layer parameters e.g., semi-statically configured byRRC message(s).

A wireless device may determine a first symbol index for one or morecandidate SS/PBCH block. For example, for a half frame with SS/PBCHblocks, the first symbol index for one or more candidate SS/PBCH blocksmay be determined according to a subcarrier spacing of the SS/PBCHblocks. For example, index 0 corresponds to the first symbol of thefirst slot in a half-frame. As an example, the first symbol of the oneor more candidate SS/PBCH blocks may have indexes {2, 8}+14·n for 15 kHzsubcarrier spacing, where, for example, n=0, 1 for carrier frequenciessmaller than or equal to 3 GHz, and for example, n=0, 1, 2, 3 forcarrier frequencies larger than 3 GHz and smaller than or equal to 6GHz. The one or more candidate SS/PBCH blocks in a half frame may beindexed in an ascending order in time, for example, from 0 to L−1. Thewireless device may determine some bits (for example, the 2 leastsignificant bits (LSB) for L=4, or the 3 LSB bits for L>4) of a SS/PBCHblock index per half frame from, for example, a one-to-one mapping withone or more index of a DM-RS sequence transmitted in the PBCH.

Prior to initiation of a random access procedure, a base station maytransmit one or more RRC messages to configure a wireless device withone or more parameters of RACH configuration, e.g., for a four-step RAprocedure, a two-step RA procedure, and/or both of four-step andtwo-step RA procedures. The one or more RRC messages may broadcast ormulticast to one or more wireless devices. The one or more RRC messagesmay be wireless device-specific messages, e.g., a dedicated RRC messagestransmitted to a wireless device with RRC INACTIVE 1520 or RRC CONNECTED1530. The one or more RRC messages may comprise one or more parametersrequired for transmitting at least one preamble via one or more randomaccess resources. For example, the one or more parameters may indicateat least one of the following: PRACH resource allocation (e.g., resourceallocation of one or more PRACH occasions), preamble format, SSBinformation (e.g., total number of SSBs, downlink resource allocation ofSSB transmission, transmission power of SSB transmission, SSB indexcorresponding to a beam transmitting the one or more RRC messages and/orother information), and/or uplink radio resources for one or moretransport block transmissions.

The base station may further transmit one or more downlink referencesignals. For example, the one or more downlink reference signals maycomprise one or more discovery reference signals. The wireless devicemay select a first downlink reference signal among the one or moredownlink reference signals. For example, the first downlink referencesignal may comprise one or more synchronization signals and a physicalbroadcast channel (SS/PBCH). For example, the wireless device may adjusta downlink synchronization based on the one or more synchronizationsignals. For example, the one or more downlink reference signals maycomprise one or more channel state information-reference signals(CSI-RS).

The one or more RRC messages may further comprise one or more parametersindicating one or more downlink control channels, for example, PDDCH.Each of the one or more downlink control channels may be associated withat least one of the one or more downlink reference signals. For example,the first downlink reference signal may comprise one or more systeminformation (e.g., master information block (MIB) and/or systeminformation block (SIB)). The base station may transmit message(s)comprising the one or more system information, for example, on thephysical broadcast channel (PBCH), physical downlink control channel(PDCCH), and/or physical downlink shared channel (PDSCH).

The one or more system information may comprise at least one informationelement (e.g., PDCCH-Config, PDCCH-ConfigSIB1, PDCCH-ConfigCommon,and/or any combination thereof). The at least one information elementmay be transmitted from a base station, for example, to indicate, to awireless device, one or more control parameters. The one or more controlparameters may indicate one or more control resource sets (CORESET). Forexample, the one or more control parameters comprises the parametersindicating a first common CORESET #0 (e.g., controlResourceSetZero),and/or a second common CORESET (e.g., commonControlResourceSet). The oneor more control parameters may further comprise one or more search spacesets. For example, the one or more control parameters comprise theparameters of a first search space for the system information block(e.g., searchSpaceSIB1), and/or a first common search space #0 (e.g.,searchSpaceZero), and/or a first random access search space (e.g.,ra-SearchSpace), and/or a first paging search space (e.g.,pagingSearchSpace). The wireless device may use the one or more controlparameters to for acquiring, configuring, and/or monitoring the one ormore downlink control channels.

A wireless device may monitor a set of one or more candidates for theone or more downlink control channels in the one or more controlresource sets. The one or more control resource sets may be defined in afirst active downlink frequency band, e.g., an active bandwidth part(BWP), on a first activated serving cell. For example, the firstactivated serving cell is configured, by a network, to a wireless devicewith the one or more search space sets. For example, the wireless devicedecodes each of the one or more downlink control channels in the set ofcandidates for the one or more downlink control channels according to afirst format of a first downlink control information (DCI). The set ofcandidates for the one or more downlink control channels may be definedin terms of the one or more search space sets. For example, the one ormore search space sets are one or more common search space sets (e.g.,Type0-PDCCH, Type0A-PDCCH, Type1-PDCCH, Type2-PDCCH, and/orType3-PDCCH), one or more wireless device-specific search space sets,and/or any combination thereof.

For example, the wireless device may monitor the set of candidates forthe one or more downlink control channels in a Type0-PDCCH common searchspace set. For example, the Type0-PDCCH common search space set may beconfigured by the at least one information element, e.g., thePDCCH-ConfigSIB1 in the MIB. For example, the Type0-PDCCH common searchspace set may be configured by the one or more search space sets, e.g.,a searchSpaceSIB1 in the PDCCH-ConfigCommon, or the searchSpaceZero inthe PDCCH-ConfigCommon. For example, the Type0-PDCCH common search spaceset may be configured for a first format of a first downlink controlinformation scrambled by a particular radio network temporaryidentifier, e.g., a system information-radio network temporaryidentifier (SI-RNTI).

For example, the wireless device may monitor the set of candidates forthe one or more downlink control channels in a Type1-PDCCH common searchspace set. For example, the Type1-PDCCH common search space set may beconfigured by the one or more search space sets, e.g., thera-searchSpace in the PDCCH-ConfigCommon. For example, the Type1-PDCCHcommon search space set may be configured for a second format of asecond downlink control information scrambled by a second radio networktemporary identifier, e.g., a random access-radio network temporaryidentifier (RA-RNTI), a temporary cell-radio network temporaryidentifier (TC-RNTI), C-RNTI, and/or an RNTI that generated by awireless device based on a two-step RA procedure, e.g., MsgB-RNTI.

The wireless device may determine, for example during a cell search,that a first control resource set for a first common search space (e.g.,Type0-PDCCH) is present. The first control resource set may comprise oneor more resource blocks and one or more symbols. The one or more RRCmessages may comprise one or more parameters indicating one or moremonitoring occasions of the one or more downlink control channels. Forexample, the wireless device determines a number of consecutive resourceblocks and a number of consecutive symbols for the first controlresource set of the first common search space. For example, one or morebits (e.g., a four most significant bits) of the at least oneinformation element (e.g., PDCCH-ConfigSIB1) indicates the number ofconsecutive resource blocks and the number of consecutive symbols. Thewireless device may determine the one or more monitoring occasions ofthe one or more downlink control channels from one or more bits (e.g., afour least significant bits) of the at least one information element(e.g., PDCCH-ConfigSIB1). For example, the one or more monitoringoccasions of the one or more downlink control channels associated with afirst downlink reference signal (e.g., SSB or CSI-RS) are determinedbased on one or more system frame numbers and one or more slot indexesof the first control resource set. For example, the first downlinkreference signal with a first index overlaps in time with the firstframe number and the first slot index.

The wireless device may select (or determine) a particular downlinkchannel from the one or more downlink control channels, based on a firstdownlink reference signal (e.g., SSB or CSI-RS). For example, thewireless device receives message(s) indicating associations between theone or more downlink control channels and one or more downlink referencesignals. The wireless device may select the first downlink referencesignal (e.g., SSB or CSI-RS) from the one or more downlink referencesignals, for example, based on an RSRP of the first downlink referencesignal larger than a first value. Based on the associations, thewireless device determine the particular downlink channel associatedwith the first downlink reference signal. The wireless device maydetermine that a demodulation reference signal antenna port associatedwith a reception of the first downlink channel is quasi co-located (QCL)with the first downlink reference signal. For example, the demodulationreference signal antenna port associated with the reception of the firstdownlink channel and the first downlink reference signal (e.g., thecorresponding SS/PBCH block) may be quasi co-located with respect to atleast one of the following: an average gain, QCL-TypeA, and/orQCL-TypeD.

A wireless device may receive, from a base station, one or more RRCmessages comprising one or more random access parameters. For example,the one or more RRC messages comprise a common (or generic) randomaccess configuration message (e.g., RACH-ConfigCommon and/orRACH-ConfigGeneric) indicating at least one of: a total number of randomaccess preambles (e.g., totalNumberOfRA-Preambles), one or more PRACHconfiguration index (e.g., prach-ConfigurationIndex), a number of PRACHoccasions that may be multiplexed in frequency domain (FDMed) in a timeinstance (e.g., msg1-FDM), an offset of a lowest PRACH occasion infrequency domain with respect to a first resource block (e.g.,msg1-FrequencyStart), a power ramping step for PRACH (e.g.,powerRampingStep), a target power level at the network receiver side(preambleReceivedTargetPower), a maximum number of random accesspreamble transmission that may be performed (e.g., preambleTransMax), awindow length for a random access response (i.e., RAR, e.g., Msg2)(e.g., ra-ResponseWindow), a number of SSBs per random access channel(RACH) occasion and a number of contention-based preambles per SSB(e.g., ssb-perRACH-OccasionAndCB-PreamblesPerSSB). For example, thetotal number of random access preambles may be a multiple of the numberof SSBs per RACH occasion. For example, the window length for RAR may bein number of slots. For example, a dedicated random access configurationmessage (e.g., RACH-ConfigDedicated) may comprise one or more RACHoccasions for contention-free random access (e.g., occasions), and oneor more PRACH mask index for random access resource selection (e.g.,ra-ssb-OccasionMaskIndex).

The one or more random access parameters (e.g.,ssb-perRACH-OccasionAndCB-PreamblesPerSSB) may indicate a first number(e.g., N) of the one or more downlink reference signals (e.g., SS/PBCHblocks) that may be associated with a first PRACH occasion. The one ormore random access parameters (e.g.,ssb-perRACH-OccasionAndCB-PreamblesPerSSB) may indicate a second number(e.g., R) of the one or more random access preambles for the firstdownlink reference signal and for the first PRACH occasion. The one ormore random access preambles may be contention based preambles. Thefirst downlink reference signal may be a first SS/PBCH block. Forexample, the first number (e.g., if N<1) indicates that the firstSS/PBCH block may be mapped to at least one (e.g., 1/N) consecutivevalid PRACH occasions. For example, the second number (e.g., R)indicates that at least one preamble with consecutive indexes associatedwith the first SS/PBCH block may start from the first preamble index forthe first valid PRACH occasion.

For example, the one or more PRACH configuration indexes (e.g.,prach-ConfigurationIndex), may indicate a preamble format, a periodicityfor the one or more PRACH time resources, one or more PRACH subframenumbers, a number of PRACH slots within the one or more PRACH subframes,a PRACH starting symbol number, and/or a number of time domain PRACHoccasions within a PRACH slot.

The one or more random access parameters may further comprise anassociation period for mapping the one or more SS/PBCH blocks to the oneor more PRACH occasions. For example, the one or more SS/PBCH blockindexes are mapped to the one or more PRACH occasions based on an order.An example of the order may be as follows: in increasing order of theindexes of the at least one preamble in the first PRACH occasion; inincreasing order of the indexes of the one or more frequency resources(e.g., for frequency multiplexed PRACH occasions); in increasing orderof the indexes of the one or more time resources (e.g., for timemultiplexed PRACH occasions) in the first PRACH slot; and/or inincreasing order of the indexes for the PRACH slots.

A control order initiating an RA procedure (e.g., for SCell additionand/or TA update) may comprising at least one PRACH mask index. The atleast PRACH mask index may indicate one or more PRACH occasionsassociated with one or more downlink reference signals (e.g., SSBsand/or CSI-RS). FIG. 18 shows an example of PRACH mask index values thatmay be indicated by the control order as per an aspect of an exampleembodiment of the present disclosure. A wireless device may identify oneor more PRACH occasion(s) of a particular downlink reference signal(e.g., SSB and/or CSI-RS) based on a PRACH mask index value indicated bythe control order (e.g., PDCCH order). The control order (e.g., PDCCH)may comprise a field indicating a particular SSB (or CSI-RS). Forexample, the allowed PRACH occasions in FIG. 18 may be mapped (e.g.,consecutively) for an index of the particular SSB. The wireless devicemay select the first PRACH occasion indicated by a first PRACH maskindex value for the particular SSB in the first association period. Thefirst association period may be a first mapping cycle. The wirelessdevice may reset the one or more indexes of the one or more PRACHoccasions for the first mapping cycle.

A wireless device may receive, from a base station, one or more messagesindicating random access parameters of a random access procedure in FIG.13A and/or FIG. 13B) and/or a two-step random access procedure in FIG.13C. For example, the one or more messages are broadcast RRC message(s),wireless device specific RRC message(s), and/or combination thereof. Forexample, the one or more message comprise at least one of random accesscommon configuration (e.g., RACH-ConfigCommon), random access genericconfiguration (e.g., RACH-ConfigGeneric), and/or random accessconfiguration dedicated to a wireless device (e.g.,RACH-ConfigDedicated). For example, for a contention based (four-stepand/or a two-step) random access procedure, a wireless device receives,from a base station, at least RACH-ConfigCommon and RACH-ConfigGeneric.For example, for a contention free (four-step and/or a two-step) randomaccess procedure, a wireless device receives, from a base station, atleast RACH-ConfigDedicated together with RACH-ConfigCommon and/orRACH-ConfigGeneric. A random access procedure on an SCell may beinitiated by a PDCCH order with ra-PreambleIndex different from a firstindex (that may be predefined or configured e.g., 0b000000).

A wireless device may initiate a random access procedure at least basedon parameter(s) configured in at least one of RACH-ConfigCommon,RACH-ConfigGeneric, and RACH-ConfigDedicated. For example, a wirelessdevice initiates a random access procedure, for example, after or inresponse to receiving a PDCCH order from a base station, by the MACentity of the wireless device and/or by RRC of the wireless device. Awireless device may be in one or more conditions based on which one ormore random access procedure need to be initiated. For example, thereexists one random access procedure ongoing at any point in time in a MACentity. A wireless device may continue with the ongoing procedure orstart with the new procedure (e.g. for SI request), for example, if anMAC entity of a wireless device receives a request for a random accessprocedure while another is already ongoing in the MAC entity.

An example random access common configuration (e.g., RACH-ConfigCommon)may be below:

RACH-ConfigCommon ::= SEQUENCE { rach-ConfigGeneric RACH-ConfigGeneric,totalNumberOfRA-Preambles INTEGER (1..63) OPTIONAL,ssb-perRACH-OccasionAndCB-PreamblesPerSSB CHOICE { oneEighth ENUMERATED{n4,n8,n12,n16,n20,n24,n28,n32,n36,n40,n44,n48,n52,n56,n60,n64},oneFourth ENUMERATED{n4,n8,n12,n16,n20,n24,n28,n32,n36,n40,n44,n48,n52,n56,n60,n64}, oneHalfENUMERATED{n4,n8,n12,n16,n20,n24,n28,n32,n36,n40,n44,n48,n52,n56,n60,n64}, oneENUMERATED{n4,n8,n12,n16,n20,n24,n28,n32,n36,n40,n44,n48,n52,n56,n60,n64}, twoENUMERATED {n4,n8,n12,n16,n20,n24,n28,n32}, four INTEGER (1..16), eightINTEGER (1..8), sixteen INTEGER (1..4) } OPTIONAL,-- Need MgroupBconfigured SEQUENCE { ra-Msg3SizeGroupA ENUMERATED { b56, b144,b208, b256, b282, b480, b640, b800, b1000, spare7, spare6, spare5,spare4, spare3, spare2, spare1}, messagePowerOffsetGroupB ENUMERATED {minusinfinity, dB0, dB5, dB8, dB10, dB12, dB15, dB18},numberOfRA-PreamblesGroupA INTEGER (1..64) } OPTIONAL,-- Need Rra-ContentionResolutionTimer ENUMERATED { sf8, sf16, sf24, sf32, sf40,sf48, sf56, sf64}, rsrp-ThresholdSSB RSRP-Range OPTIONAL, -- Need Rrsrp-ThresholdSSB-SUL RSRP-Range OPTIONAL, -- Cond SULprach-RootSequenceIndex CHOICE { l839 INTEGER (0..837), l139 INTEGER(0..137) }, msg1-SubcarrierSpacing SubcarrierSpacing OPTIONAL, --Need SrestrictedSetConfig ENUMERATED {unrestrictedSet, restrictedSetTypeA,restrictedSetTypeB}, msg3-transformPrecoding ENUMERATED {enabled}OPTIONAL, -- Need R, ... }

For example, messagePowerOffsetGroupB indicates a threshold for preambleselection. The value of messagePowerOffsetGroupB may be in dB. Forexample, minusinfinity in RACH-ConfigCommon corresponds to infinity. Thevalue dB0 may correspond to 0 dB, dB5 may correspond to 5 dB and so on.msg1-SubcarrierSpacing in RACH-ConfigCommon may indicate a subcarrierspacing of PRACH. One or more values, e.g., 15 or 30 kHz (<6 GHz), 60 or120 kHz (>6 GHz) may be applicable. There may be a layer 1 parameter(e.g., ‘prach-Msg1SubcarrierSpacing) corresponding tomsg1-SubcarrierSpacing. A wireless device may apply the SCS as derivedfrom the prach-ConfigurationIndex in RACH-ConfigGeneric, for example, ifthis parameter is absent. A base station may employmsg3-transformPrecoding to indicate to a wireless device whethertransform precoding is enabled for data transmission (e.g., Msg3 in afour-step RA procedure and/or one or more TB transmission in a two-stepRA procedure). Absence of msg3-transfromPrecoding may indicate that itis disabled. numberOfRA-PreamblesGroupA may indicate a number ofcontention based (CB) preambles per SSB in group A. This may determineimplicitly the number of CB preambles per SSB available in group B. Thesetting may be consistent with the setting ofssb-perRACH-OccasionAndCB-PreamblesPerSSB. prach-RootSequenceIndex mayindicate PRACH root sequence index. There may be a layer 1 parameter(e.g., ‘PRACHRootSequenceIndex’) corresponding tossb-perRACH-OccasionAndCB-PreamblePerSSB. The value range may depend ona size of preamble, e.g., whether a preamble length (L) is L=839 orL=139. ra-ContentionResolutionTimer may indicate an initial value forthe contention resolution timer. For example, a value ms8 inRACH-ConfigCommon may indicate 8 ms, value ms16 may indicate 16 ms, andso on. ra-Msg3SizeGroupA may indicate a transport blocks size thresholdin bit. For example, a wireless device may employ a contention based RApreamble of group A, for example, when the transport block size is belowra-Msg3SizeGroupA. rach-ConfigGeneric may indicate one or more genericRACH parameters in RACH-ConfigGeneric. restrictedSetConfig may indicatea configuration of an unrestricted set or one of two types of restrictedsets. rsrp-ThresholdSSB may indicate a threshold for SS block selection.For example, a wireless device may select the SS block and correspondingPRACH resource for path-loss estimation and (re)transmission based on SSblocks that satisfy the threshold. rsrp-ThresholdSSB-SUL may indicate athreshold for uplink carrier selection. For example, a wireless devicemay select a supplementary uplink (SUL) carrier to perform random accessbased on this threshold. ssb-perRACH-OccasionAndCB-PreamblesPerSSB mayindicate a number of SSBs per RACH occasion and a number of contentionbased preambles per SSB. There may be layer 1 one or more parameters(e.g., ‘SSB-per-rach-occasion’ and/or ‘CB-preambles-per-SSB’)corresponding to ssb-perRACH-OccasionAndCB-PreamblesPerSSB. For example,a total number of CB preambles in a RACH occasion may be given byCB-preambles-per-SSB*max(1,SSB-per-rach-occasion).totalNumberOfRA-Preambles may indicate a total number of preamblesemployed for contention based and contention free random access. Forexample, totalNumberOfRA-Preambles may not comprise one or morepreambles employed for other purposes (e.g. for SI request). A wirelessdevice may use one or more of 64 preambles for RA, for example, if thefield is absent.

An example random access common configuration of RACH-ConfigGeneric maybe below:

RACH-ConfigGeneric ::= SEQUENCE { prach-ConfigurationIndex INTEGER(0..255), msg1-FDM ENUMERATED {one, two, four, eight},msg1-FrequencyStart INTEGER (0..maxNrofPhysicalResourceBlocks−1),zeroCorrelationZoneConfig INTEGER(0..15), preambleReceivedTargetPowerINTEGER (−202..−60), preambleTransMax ENUMERATED {n3, n4, n5, n6, n7,n8,n10, n20, n50, n100, n200}, powerRampingStep ENUMERATED {dB0, dB2, dB4,dB6}, ra-ResponseWindow ENUMERATED {sl1, sl2, sl4, sl8, sl10, sl20,sl40, sl80},... }

For example, msg1-FDM may indicate a number of PRACH transmissionoccasions FDMed in one time instance. There may be a layer 1 parameter(e.g., ‘prach-FDM’) corresponding to msg1-FDM. msg1-FrequencyStart mayindicate an offset of PRACH transmission occasion (e.g., lowest PRACHtransmission occasion) in frequency domain with respective to aparticular PRB (e.g., PRB 0). A base station may configure a value ofmsg1-FrequencyStart such that the corresponding RACH resource is withinthe bandwidth of the UL BWP. There may be a layer 1 parameter (e.g.,‘prach-frequency-start’) corresponding to msg1-FreqencyStart.powerRampingStep may indicate power ramping steps for PRACH.prach-ConfigurationIndex may indicate a PRACH configuration index. Forexample, a radio access technology (e.g., LTE, and/or NR) may predefineone or more PRACH configurations, and prach-ConfigurationIndex mayindicate one of the one or more PRACH configurations. There may be alayer 1 parameter (e.g., ‘PRACHConfigurationIndex’) corresponding toprach-ConfigurationIndex. preambleReceivedTargetPower may indicate atarget power level at the network receiver side. For example, multiplesof a particular value (e.g., in dBm) may be chosen. RACH-ConfigGenericabove shows an example when multiples of 2 dBm are chosen (e.g. −202,−200, −198, . . . ). preambleTransMax may indicate a number of RApreamble transmissions performed before declaring a failure. Forexample, preambleTransMax may indicate a maximum number of RA preambletransmissions performed before declaring a failure. ra-ResponseWindowmay indicate an RAR window length in number of slots (or subframes,mini-slots, and/or symbols). a base station may configure a value lowerthan or equal to a particular value (e.g., 10 ms). The value may belarger than a particular value (e.g., 10 ms). zeroCorrelationZoneConfigmay indicate an index of preamble sequence generation configuration(e.g., N-CS configuration). A radio access technology (e.g., LTE and/orNR) may predefine one or more preamble sequence generationconfigurations, and zeroCorrelationZoneConfig may indicate one of theone or more preamble sequence generation configurations. For example, awireless device may determine a cyclic shift of preamble sequence basedon zeroCorrelationZoneConfig. zeroCorrelationZoneConfig may determine aproperty of random access preambles (e.g., a zero correlation zone)

An example random access dedicated configuration (e.g.,RACH-ConfigDedicated) may be below:

RACH-ConfigDedicated ::= SEQUENCE { cfra CFRA OPTIONAL, -- Need Nra-Prioritization RA-Prioritization OPTIONAL, -- Need N ... } CFRA ::=SEQUENCE { occasions SEQUENCE { rach-ConfigGeneric RACH-ConfigGeneric,ssb-perRACH-Occasion ENUMERATED {oneEighth, oneFourth, oneHalf, one,two, four, eight, sixteen} OPTIONAL -- Cond SSB-CFRA } OPTIONAL,-- NeedS resources CHOICE { ssb SEQUENCE {  ssb-ResourceList SEQUENCE(SIZE(1..maxRA-SSB-Resources)) OF CFRA-SSB-Resource, ra-ssb-OccasionMaskIndex INTEGER (0..15) }, csirs SEQUENCE { csirs-ResourceList SEQUENCE (SIZE(1..maxRA-CSIRS-Resources)) OFCFRA-CSIRS-Resource,  rsrp-ThresholdCSI-RS RSRP-Range } }, ... }CFRA-SSB-Resource ::= SEQUENCE { ssb SSB-Index, ra-PreambleIndex INTEGER(0..63), ... } CFRA-CSIRS-Resource ::= SEQUENCE { csi-RS CSI-RS-Index,ra-OccasionList SEQUENCE (SIZE(1..maxRA-OccasionsPerCSIRS)) OF INTEGER(0..maxRA-Occasions−1), ra-PreambleIndex INTEGER (0..63), ... }

For example, a CSI-RS is indicated, to a wireless device, by anidentifier (e.g., ID) of a CSI-RS resource defined in the measurementobject associated with this serving cell. ra-OccasionList may indicateone or more RA occasions. A wireless device may employ the one or moreRA occasions, for example, when the wireless device performs acontention-free random access (CFRA) procedure upon selecting thecandidate beam identified by the CSI-RS. ra-PreambleIndex may indicatean RA preamble index to use in the RA occasions associated with thisCSI-RS. ra-ssb-OccasionMaskIndex may indicate a PRACH Mask Index for RAResource selection. The mask may be valid for one or more SSB resourcessignaled in ssb-ResourceList. rach-ConfigGeneric may indicate aconfiguration of contention free random access occasions for the CFRAprocedure. ssb-perRACH-Occasion may indicate a number of SSBs per RACHoccasion. ra-PreambleIndex may indicate a preamble index that a wirelessdevice may employ when performing CFRA upon selecting the candidatebeams identified by this SSB. ssb in RACH-ConfigDedicated may indicatean identifier (e.g., ID) of an SSB transmitted by this serving cell.cfra in RACH-ConfigDedicated may indicate one or more parameters forcontention free random access to a given target cell. A wireless devicemay perform contention based random access, for example, if the field(e.g., cfra) is absent. ra-prioritization may indicate one or moreparameters which apply for prioritized random access procedure to agiven target cell. A field, SSB-CFRA, in RACH-ConfigDedicated may bepresent, for example, if the field resources in CFRA is set to ssb;otherwise it may be not present.

A wireless device may receive, from a base station, one or more RRCmessage indicating at least one of:

an available set of PRACH occasions for the transmission of the RandomAccess Preamble (e.g., prach-ConfigIndex), an initial Random AccessPreamble power (e.g., preambleReceivedTargetPower), an RSRP thresholdfor the selection of the SSB and corresponding Random Access Preambleand/or PRACH occasion (e.g., rsrp-ThresholdSSB, rsrp-ThresholdSSB may beconfigured in a beam failure recovery configuration, e.g.,BeamFailureRecoveryConfig IE, for example, if the Random Accessprocedure is initiated for beam failure recovery), an RSRP threshold forthe selection of CSI-RS and corresponding Random Access Preamble and/orPRACH occasion (e.g., rsrp-ThresholdCSI-RS, rsrp-ThresholdCSI-RS may beset to a value calculated based on rsrp-ThresholdSSB and an offsetvalue, e.g., by multiplying rsrp-ThresholdSSB by powerControlOffset), anRSRP threshold for the selection between the NUL carrier and the SULcarrier (e.g., rsrp-ThresholdSSB-SUL), a power offset betweenrsrp-ThresholdSSB and rsrp-ThresholdCSI-RS to be employed when theRandom Access procedure is initiated for beam failure recovery (e.g.,powerControlOffset), a power-ramping factor (e.g., powerRampingStep), apower-ramping factor in case of differentiated Random Access procedure(e.g., powerRampingStepHighPriority), an index of Random Access Preamble(e.g., ra-PreambleIndex), an index (e.g., ra-ssb-OccasionMaskIndex)indicating PRACH occasion(s) associated with an SSB in which the MACentity may transmit a Random Access Preamble (e.g., FIG. 18 shows anexample of ra-ssb-OccasionMaskIndex values), PRACH occasion(s)associated with a CSI-RS in which the MAC entity may transmit a RandomAccess Preamble (e.g., ra-OccasionList), a maximum number of RandomAccess Preamble transmission (e.g., preambleTransMax), a number of SSBsmapped to each PRACH occasion and a number of Random Access Preamblesmapped to each SSB (e.g., ssb-perRACH-OccasionAndCB-PreamblesPerSSB, thetime window (duration, and/or interval) to monitor RA response(s) (e.g.,ra-ResponseWindow) and/or a Contention Resolution Timer (e.g.,ra-ContentionResolutionTimer).

In an example, a wireless device initiates an RA procedure for beamfailure detection and recovery. For example, a wireless device receives,from a base station, RRC message(s) for a beam failure recoveryprocedure. The wireless device may indicate, to the serving base stationbased on the beam failure recovery procedure, SSB(s) or CSI-RS(s) onwhich the wireless device detects a beam failure among one or moreserving SSB(s)/CSI-RS(s). Beam failure may be detected by counting oneor more beam failure instance indication from the lower layers to theMAC entity of the wireless device. For example, a wireless devicereceive, from a base station, an RRC message (e.g., comprising a beamfailure recovery configuration, e.g., BeamFailureRecoveryConfig)indicating at least one of following: beamFailureInstanceMaxCount forthe beam failure detection. beamFailureDetectionTimer for the beamfailure detection, beamFailureRecoveryTimer for the beam failurerecovery procedure, rsrp-ThresholdSSB for an RSRP threshold for the beamfailure recovery, powerRampingStep for the beam failure recovery,preambleReceivedTargetPower, preambleReceivedTargetPower for the beamfailure recovery, preambleTransMax for the beam failure recovery, thetime window (e.g., ra-ResponseWindow) to monitor response(s) for thebeam failure recovery using contention-free Random Access Preamble,prach-ConfigIndex for the beam failure recovery,ra-ssb-OccasionMaskIndex for the beam failure recovery, ra-OccasionListfor the beam failure recovery.

A wireless device may employ (or use or maintain) one or more parameters(or variables) for a random access procedure. For example, the one ormore parameters (or variables) comprise at least one of: PREAMBLE_INDEX;PREAMBLE_TRANSMISSION_COUNTER; PREAMBLE_POWER_RAMPING_COUNTER;PREAMBLE_POWER_RAMPING_STEP; PREAMBLE_RECEIVED_TARGET_POWER;PREAMBLE_BACKOFF; PCMAX; SCALING_FACTOR_BI; and TEMPORARY_C-RNTI.

A wireless device may perform a random access resource selection forselecting one or more preambles and one or more PRACH occasion (orresources comprising time, frequency, and/or code). For example, theremay be one or more cases that a random access procedure may be initiatedfor beam failure recovery; and/or the beamFailureRecoveryTimer is eitherrunning or not configured; and/or the contention-free Random AccessResources for beam failure recovery request associated with any of theSSBs and/or CSI-RSs have been explicitly provided by RRC; and/or atleast one of the SSBs with SS-RSRP above rsrp-ThresholdSSB amongst theSSBs in candidateBeamRSList or the CSI-RSs with CSI-RSRP aboversrp-ThresholdCSI-RS amongst the CSI-RSs in candidateBeamRSList isavailable. In this case, a wireless device may select one or more SSBswith corresponding one or more SS-RSRP values above rsrp-ThresholdSSBamongst the SSBs in candidateBeamRSList or one or more CSI-RSs withcorresponding one or more CSI-RSRP values above rsrp-ThresholdCSI-RSamongst the CSI-RSs in candidateBeamRSList. For example, a wirelessdevice may select at least one CSI-RS and set the PREAMBLE_INDEX to ara-PreambleIndex corresponding to the SSB in candidateBeamRSList whichis quasi-collocated with the at least one CSI-RS selected by thewireless device, for example, if there is no ra-PreambleIndex associatedwith the at least one CSI-RS, otherwise the wireless device may set thePREAMBLE_INDEX to a ra-PreambleIndex corresponding to the selected SSBor CSI-RS from the set of Random Access Preambles for beam failurerecovery request.

A wireless device may receive, via PDCCH or RRC, a ra-PreambleIndexwhich is not a particular preamble index (that may be predefined orconfigured e.g., 0b000000). In this case, the wireless device may setthe PREAMBLE_INDEX to the signaled ra-PreambleIndex.

There may be one or more cases that the contention-free Random AccessResources associated with SSBs have been explicitly provided, to awireless device via RRC, and at least one SSB with SS-RSRP aboversrp-ThresholdSSB amongst the associated SSBs is available. In thiscase, the wireless device may select an SSB with SS-RSRP aboversrp-ThresholdSSB amongst the associated SSBs. For example, the wirelessdevice sets the PREAMBLE_INDEX to a ra-PreambleIndex corresponding tothe selected SSB.

There may be one or more cases that the contention-free random accessresources associated with CSI-RSs have been explicitly provided, to awireless device via RRC, and at least one CSI-RS with CSI-RS RSRP aboversrp-ThresholdCSI-RS amongst the associated CSI-RSs is available. Inthis case, a wireless device may select a CSI-RS with CSI-RSRP aboversrp-ThresholdCSI-RS amongst the associated CSI-RSs. For example, thewireless device sets the PREAMBLE_INDEX to a ra-PreambleIndexcorresponding to the selected CSI-RS.

There may be one or more cases that at least one of the SSBs withSS-RSRP above rsrp-ThresholdSSB is available. In this case, for example,a wireless device may select an SSB with SS-RSRP aboversrp-ThresholdSSB. The wireless device may select any SSB, e.g., if noneof the SSBs with SS-RSRP above rsrp-ThresholdSSB is available. Forexample, a random access resource selection is performed, e.g., when aretransmission of Msg1 1311, Msg3 1313, MsgA 1331, and/or Transportblock 1342. The wireless device may select the same group of RandomAccess Preambles as was employed for the Random Access Preambletransmission attempt corresponding to the first transmission of the Msg11311, the Msg3 1313, the MsgA 1331, and/or the Transport block 1342. Forexample, a wireless device selects a ra-PreambleIndex randomly withequal probability from the Random Access Preambles associated with theselected SSB and the selected Random Access Preambles group, e.g., ifthe association between random access preambles and SSBs is configured.For example, a wireless device selects a ra-PreambleIndex randomly withequal probability from the Random Access Preambles within the selectedRandom Access Preambles group, e.g., if the association between randomaccess preambles and SSBs is not configured. The wireless device may setthe PREAMBLE_INDEX to the selected ra-PreambleIndex.

In an example, if an SSB is selected above and an association betweenPRACH occasions and SSBs is configured, a wireless device determines thenext available PRACH occasion from the PRACH occasions corresponding tothe selected SSB permitted by the restrictions given by thera-ssb-OccasionMaskIndex if configured (e.g., the MAC entity of thewireless device may select a PRACH occasion (e.g., randomly with equalprobability) amongst the PRACH occasions occurring simultaneously but ondifferent subcarriers, corresponding to the selected SSB; the MAC entitymay take into account the possible occurrence of measurement gaps whendetermining the next available PRACH occasion corresponding to theselected SSB).

In an example, if a CSI-RS is selected above and an association betweenPRACH occasions and CSI-RSs is configured. a wireless device determinesthe next available PRACH occasion from the PRACH occasions inra-OccasionList corresponding to the selected CSI-RS (e.g. the MACentity of the wireless device may select a PRACH occasion randomly withequal probability amongst the PRACH occasions occurring simultaneouslybut on different subcarriers, corresponding to the selected CSI-RS; theMAC entity may take into account the possible occurrence of measurementgaps when determining the next available PRACH occasion corresponding tothe selected CSI-RS).

If a CSI-RS is selected above and there is no contention-free RandomAccess Resource associated with the selected CSI-RS, a wireless devicemay determine the next available PRACH occasion from the PRACHoccasions, for example, indicated by the ra-ssb-OccasionMaskIndex ifconfigured (e.g., ra-ssb-OccasionMaskIndex may indicate the restrictionspermitting which PRACH occasions available), corresponding to the SSB incandidateBeamRSList which is quasi-collocated with the selected CSI-RS(e.g., the MAC entity of the wireless device may take into account thepossible occurrence of measurement gaps when determining the nextavailable PRACH occasion corresponding to the SSB which isquasi-collocated with the selected CSI-RS).

A wireless device may determine the next available PRACH occasion. Forexample, an MAC entity of the wireless device selects a PRACH occasion(e.g., randomly with equal probability) amongst the PRACH occasionsoccurring simultaneously but on different subcarriers. The MAC entitymay determine the next available PRACH occasion based on (e.g., bytaking into account) the possible occurrence of measurement gaps.

A wireless device may perform the random access preamble transmissionbased on a selected PREABLE INDEX and PRACH occasion. For example, ifthe notification of suspending power ramping counter has not beenreceived from lower layers (e.g., physical layer); and/or if an SSBand/or a CSI-RS selected is not changed (e.g., same as the previousRandom Access Preamble transmission), a wireless device may incrementPREAMBLE_POWER_RAMPING_COUNTER, e.g., by one or to the next value (e.g.,counter step size may be predefined and/or semi-statically configured).For example, the wireless device selects a value of DELTA_PREAMBLE thatmay be predefined and/or semi-statically configured by a base stationand set PREAMBLE_RECEIVED_TARGET_POWER topreambleReceivedTargetPower+DELTA_PREAMBLE+(PREAMBLE_POWER_RAMPING_COUNTER−1)×PREAMBLE_POWER_RAMPING_STEP.

An MAC entity of the wireless device may instruct the physical layer totransmit the Random Access Preamble using the selected PRACH,corresponding RA-RNTI (e.g., if available), PREAMBLE_INDEX andPREAMBLE_RECEIVED_TARGET_POWER. For example, the wireless devicedetermines an RA-RNTI associated with the PRACH occasion in which theRandom Access Preamble is transmitted. In an example, the RA-RNTI may bedetermined in terms of index of the first OFDM symbol of the specifiedPRACH, an index of the first slot of the specified PRACH in a systemframe, an index of the specified PRACH in the frequency domain, and/oruplink carrier indicator. For example, the specified PRACH is a PRACH inwhich the wireless device transmits the Random Access Preamble. Anexample RA-RNTI is determined as:RA-RNTI=1+s_id+14×t_id+14×80×f_id+14×80×8×ul_carrier_idwhere s_id may be the index of the first OFDM symbol of the specifiedPRACH (0≤s_id<14), t_id may be the index of the first slot of thespecified PRACH in a system frame (0≤t_id<80), f_id may be the index ofthe specified PRACH in the frequency domain (0≤f_id<8), andul_carrier_id (0 for NUL carrier, and 1 for SUL carrier or vice versa)may be the UL carrier used for Msg1 1311 transmission or Preamble 1341.In an unlicensed band, RA-RNTI may be determined further based on a SFNand/or RAR window size. For example, the RA-RNTI may be determinedfurther based on a remainder after division of the SFN by the RAR windowsize (e.g., the SFN modulo the RAR window size). An example RA-RNTIdetermination in an unlicensed band may beRA-RNTI=1+s_id+14×t_id+14×80×f_id+14×80×8×ul_carrier_id×14×80×8×2×(SFNmodulo RAR window size),where the SFN is a system frame number of the first slot and RAR windowsize is configured by a higher layer parameter, e.g., ra-ResponseWindowin RACH-ConfigGeneric. For example, depending on implementation, (SFNmodulo RAR window size) may be located before any of components, s_id,14×t_id, 14×80×f_id, and/or 14×80×8×ul_carrier_id in the RA-RNTIcalculation formula.

A wireless device, that transmitted a random access preamble, may startto monitor a downlink control channel for a random access responsecorresponding to the random access preamble. For a two-step RAprocedure, the wireless device may start to monitor the downlink controlchannel, e.g., after or in response to transmitting an RAP via PRACH orafter or in response to transmitting one or more TBs via PUSCH. Thepossible occurrence of a measurement gap may not determine when awireless device starts to monitor a downlink control channel.

A wireless device may start a random access window (e.g.,ra-ResponseWindow) configured in a beam management configurationparameters (e.g., BeamFailureRecoveryConfig) at a first downlink controlchannel (e.g., PDCCH) occasion from the end of the Random AccessPreamble transmission (e.g., Msg1 1311 or Msg1 1321 for a case offour-step RA procedure) or from the end of transmission of one or moreTBs (e.g., Transport block 1342 for a case of two-step RA procedure),e.g., if the wireless device performs a contention-free random accessprocedure for a beam failure recovery request. The wireless device maymonitor the first downlink control channel of the SpCell for a responseto beam failure recovery request identified by a particular RNTI (e.g.,RA-RNTI or C-RNTI) while the random access window is running.

A wireless device may start a random access window (e.g.,ra-ResponseWindow) configured in a random access configuration parameter(e.g., RACH-ConfigCommon) at a first downlink control channel occasionfrom an end of a random access preamble transmission (e.g., Msg1 1311 orMsg1 1321 for a case of four-step RA procedure) or from an end of one ormore TBs transmission (e.g., Transport block 1342 for a case of two-stepRA procedure), e.g., if a wireless device does not perform acontention-free random access procedure for beam a failure recoveryrequest. The wireless device may monitor the first downlink controlchannel occasion of the SpCell for random access response(s) identifiedby a particular RNTI (e.g., RA-RNTI or C-RNTI) while a random accessresponse window (e.g., ra-ResponseWindow) is running.

A wireless device may receive a PDCCH based on the RA-RNTI. The PDCCHmay indicate a downlink assignment based on which the wireless devicemay receive one or more TBs comprising an MAC PDU. For example, the MACPDU comprises at least one MAC subPDU with a corresponding subheadercomprising a Random Access Preamble identifier (e.g., RAPID) matched toa preamble that a wireless device transmits to a base station. In thiscase, the wireless device may determine that a random access responsereception is successful. For example, the at least one MAC subPDUcomprises a Random Access Preamble identifier (e.g., RAPID) only, e.g.,for a random access procedure that a wireless device initiates for asystem information request.

In an RA procedure, a wireless device may receive from a base station atleast one RAR (e.g., Msg2 1312, Msg2 1322, or MsgB 1332) as a responseof Msg1 1313, Msg1 1321, or MsgA 1331. The wireless device may monitor asearch space set (e.g., the Type1-PDCCH common search space) for a firstdownlink control information (e.g., DCI format 1_0). The first downlinkcontrol information may be scrambled by a particular radio networktemporary identifier (e.g., RA-RNTI, C-RNTI, or msgB-RNTI). The firstdownlink control information may comprise a downlink assignmentindicating scheduling of PDSCH comprising the at least one RAR. Thewireless device may use the downlink assignment to identify parametersrequired for decoding/detecting the PDSCH. For example, the downlinkassignment indicates at least one of following: time and frequencyresource allocation of the PDSCH, a size of the PDSCH, MCS, etc. Thewireless device may receive the PDSCH comprising the at least one RARbased on the parameters.

A wireless device may monitor for the first downlink control information(e.g., DCI format 1_0) during a time window. The time window may beindicated by the one or more RRC messages. For example, the time windowstarts at a particular symbol (e.g., a first or a last symbol) of afirst control resource set. The wireless device may receive, from anetwork or base station, one or more RRC messages comprising one or moreparameters required for receiving the first downlink control informationon the first control resource set. The wireless device may determine alength of the time window based on the one or more parameters (e.g.,ra-ResponseWindow). The length of the time window may be defined interms of a number of slots, OFDM symbols, and/or any combinationthereof. In this case, the length may depends on a duration of slotand/or OFDM symbol that may be determined based on a numerology. Thelength of the time window may be defined based on an absolute timeduration, e.g., in terms of millisecond(s).

The wireless device may stop the time window, e.g., after or in responseto a reception of the one or more random access responses beingdetermined as successful. A reception of the one or more random accessresponses may be determined as successful, for example, when the one ormore random access responses comprise a preamble index (e.g., a randomaccess preamble identity: RAPID) corresponding to a preamble that thewireless device transmits to a base station. For example, the RAPID maybe associated with the PRACH transmission. The one or more random accessresponses may comprise an uplink grant indicating one or more uplinkresources granted for the wireless device. The wireless device maytransmit one or more transport blocks (e.g., Msg 3 1313) via the one ormore uplink resources.

An RAR may be in a form of MAC PDU comprising one or more MAC subPDUsand/or optionally padding. FIG. 19A is an example of an RAR as per anaspect of an example embodiment of the present disclosure. A MACsubheader may be octet aligned. Each MAC subPDU may comprise at leastone of following: a MAC subheader with Backoff Indicator only; a MACsubheader with RAPID only (i.e. acknowledgment for SI request); a MACsubheader with RAPID and MAC RAR. FIG. 19B is an example of a MACsubheader with backoff indicator as per an aspect of an exampleembodiment of the present disclosure. For example, a MAC subheader withbackoff indicator comprise one or more header fields, e.g., E/T/R/R/BIas described in FIG. 19B. A MAC subPDU with backoff indicator may beplaced at the beginning of the MAC PDU, for example, if the MAC subPDUcomprises the backoff indicator. MAC subPDU(s) with RAPID only and MACsubPDU(s) with RAPID and MAC RAR may be placed anywhere after MAC subPDUwith Backoff Indicator and, if exist before padding as described in FIG.19A. A MAC subheader with RAPID may comprise one or more header fields,e.g., E/T/RAPID as described in FIG. 19C as per an aspect of an exampleembodiment of the present disclosure. Padding may be placed at the endof the MAC PDU if present. Presence and length of padding may beimplicit based on TB size, size of MAC subPDU(s).

In an example, one or more header fields in a MAC subheader may indicateas follow: an E field may indicate an extension field that may be a flagindicating if the MAC subPDU including this MAC subheader is the lastMAC subPDU or not in the MAC PDU. The E field may be set to “1” toindicate at least another MAC subPDU follows. The E field may be set to“0” to indicate that the MAC subPDU including this MAC subheader is thelast MAC subPDU in the MAC PDU; a T filed may be a flag indicatingwhether the MAC subheader contains a Random Access Preamble ID or aBackoff Indicator (one or more backoff values may predefined and BI mayindicate one of backoff value). The T field may be set to “0” toindicate the presence of a Backoff Indicator field in the subheader(BI). The T field may be set to “1” to indicate the presence of a RandomAccess Preamble ID field in the subheader (RAPID); an R filed mayindicate a reserved bit that may be set to “0”; a BI field may be abackoff indicator field that identifies the overload condition in thecell. The size of the BI field may be 4 bits; an RAPID field may be aRandom Access Preamble IDentifier field that may identify thetransmitted Random Access Preamble. The MAC subPDU may not comprise aMAC RAR, for example, if the RAPID in the MAC subheader of a MAC subPDUcorresponds to one of the Random Access Preambles configured for SIrequest.

There may be one or more MAC RAR format. At least one of following MACRAR format may be employed in a four-step or a two-step RA procedure.For example, FIG. 20 is an example of one of MAC RAR formats as per anaspect of an example embodiment of the present disclosure. The MAC RARmay be fixed size as depicted in FIG. 20 and may comprise at least oneof the following fields: an R field that may indicate a Reserved bit,set to “0” or “1”; a Timing Advance Command field that may indicate theindex value TA employed to control the amount of timing adjustment; a ULGrant field that indicate the resources to be employed on the uplink;and an RNTI field (e.g., Temporary C-RNTI and/or C-RNTI) that mayindicate an identity that is employed during Random Access. For example,for a two-step RA procedure, an RAR may comprise at least one offollowing: a UE contention resolution identity, an RV ID forretransmission of one or more TBs, decoding success or failure indicatorof one or more TB transmission, and one or more fields shown in FIG. 20.

There may be a case that a base station may multiplex, in a MAC PDU,RARs for two-step and four-step RA procedures. A wireless device may notrequire an RAR length indicator field and/or the wireless device maydetermine the boundary of each RAR in the MAC PDU based onpre-determined RAR size information, e.g., if RARs for two-step andfour-step RA procedure have the same size. For example, FIG. 21 is anexample RAR format that may be employed in a MAC PDU multiplexing an RARfor two-step and an RAR four-step RA procedures as per an aspect of anexample embodiment of the present disclosure. The RAR shown in FIG. 21may be a fixed size using the same format for two-step and four-step RAprocedures. A wireless device may use (parse, interpret, or determine) abit string (e.g., 6 octets) of the field for UE contention resolutionidentity in FIG. 21 differently depending on a type of RA procedure. Forexample, a wireless device initiating a two-step RA procedure identifieswhether a contention resolution is successful (e.g., is resolved ormade) or not based on the bit string, e.g., by comparing a contentionresolution identifier with the bit string (e.g., 6 octets) of the fieldfor UE contention resolution identity. For example, a wireless deviceinitiating a four-step RA procedure uses (parses, interprets, ordetermines) a bit string (e.g., 6 octets) differently, e.g., other thana contention resolution purpose. For example, in this case, the bitstring may indicate another UL grant for additional one or more Msg31313 transmission opportunities, padding bits, etc.

In an example, an RAR for a two-step RA procedure may have formats,sizes, and/or fields different from an RAR for a four-step RA procedure.For example, FIG. 22A, and FIG. 22B are example RAR formats that may beemployed for a two-step RA procedure as per an aspect of an exampleembodiment of the present disclosure. An RAR may comprise a field (e.g.,a reserved “R” field as shown in FIG. 21 , FIG. 22A, and FIG. 22B)indicating a type of RAR or a length of RAR, e.g., if one or more RARare (e.g., RARs for two-step and four-step RA procedures) aremultiplexed into a MAC PDU, and the RARs have different formats betweenmultiplexed RARs (e.g., between two-step RA procedure and/or betweentwo-step and four-step RA procedure). A field for indicating an RAR type(or length) may be in a subheader (such as a MAC subheader), in an MACRAR, or in a separate MAC subPDU in the RAR (e.g., like MAC subPDU 1and/or MAC subPDU 2 in FIG. 19A, there may be another MAC subPDUindicating the RAR type (or length)). An RAR may comprise differenttypes of fields that may correspond with an implicit and/or explicitindicator in a subheader or in an RAR. A wireless device may determinethe boundary of one or more RARs in a MAC PDU based on one or moreindicators.

There may be a random access response window where a wireless device maymonitor a downlink control channel for a random access responsetransmitted from a base station as a response to a preamble receivedfrom the wireless device. For example, a base station may transmit amessage comprising a value of an RAR window. For example, a cell-commonor wireless device specific random access configuration parameters(e.g., RACH-ConfigGeneric, RACH-ConfigCommon, RACH-ConfigDedicated, orServingCellConfig) in the message indicates a value of an RAR window(e.g., ra-ResponseWindow). For example, the value of an RAR window isfixed, for example, to 10 ms or other time value. For example, the valueof an RAR window is defined in terms of a number of slots as shown inRACH-ConfigGeneric. A wireless device may identify (or determine) a size(e.g., absolute time duration, and/or length) of an RAR window based ona numerology configured for a random access procedure. For example, anumerology defines one or more system parameters such as subcarrierspacing, slot duration, cyclic prefix size, number of OFDM symbol perslot, number of slots per frame, number of slots per subframe, minimumnumber of physical resource blocks, and/or maximum number of physicalresource blocks. For example, the one or more system parametersassociated with a numerology may be predefined with different subcarrierspacing, slot duration, and/or cyclic prefix size. For example, awireless device may identify a subcarrier spacing 15 kHz, normal cyclicprefix, 14 symbols per slot, 10 slots per frame, and/or 1 slot persubframe for the numerologies μ=0. For example, a wireless device mayidentify a subcarrier spacing 30 kHz, normal cyclic prefix, 14 symbolsper slot, 20 slots per frame, and/or 2 slot per subframe for thenumerologies μ=1. For example, a wireless device may identify asubcarrier spacing 60 kHz, 14 symbols per slot, 40 slots per frame,and/or 4 slot per subframe for the numerologies μ=2 with normal cyclicprefix. For example, a wireless device may identify a subcarrier spacing60 kHz, 12 symbols per slot, 40 slots per frame, and/or 4 slot persubframe for the numerologies μ=2 with extended cyclic prefix. Forexample, a wireless device may identify a subcarrier spacing 120 kHz,normal cyclic prefix, 14 symbols per slot, 80 slots per frame, and/or 8slot per subframe for the numerologies μ=3. For example, a wirelessdevice may identify a subcarrier spacing 240 kHz, normal cyclic prefix,14 symbols per slot, 160 slots per frame, and/or 16 slot per subframefor the numerologies μ=4.

A wireless device may determine (or identify) a size (e.g., duration orlength) of the RAR window based on a configured RAR window value and anumerology. For example, the RAR window has a duration of 20 ms, e.g.,if the configured RAR window value is sl20 (e.g., 20 slots) and thenumerology is μ=0 (e.g., slot duration for μ=0 is 1 ms). In an example,a particular RAR window value (e.g., ra-ResponseWindow) configured by anRRC message (e.g., broadcast and/or wireless specific unicast) may beassociated with a particular numerology. For example, inRACH-ConfigGeneric, sl10, sl20, sl40, and sl80 may be values ofra-ResponseWindow for numerologies μ=0, =1, =2, and =3, respectively. Inan example, a base station configures a wireless device a particular RARwindow value independent of a numerology. In an licensed band, a size(e.g., duration or length) of an RAR window may not be longer than 10 ms(and/or a periodicity of PRACH occasion). In an unlicensed band, aduration (e.g., size or length) of an RAR window may be longer than 10ms (and/or a periodicity of PRACH occasion).

A wireless device may perform one or more retransmission of one or morepreambles during a random access procedure (e.g., two-step RA procedureand/or four-step RA procedure). There may be one or more conditions atleast based on which the wireless device determines the one or moreretransmission of one or more preambles. The wireless device maydetermine the one or more retransmission of one or more preambles, e.g.,when the wireless device determines that a random access responsereception is not successful. The wireless device may determine that arandom access response reception is not successful, e.g., if at leastone random access response comprising one or more random access preambleidentifiers that matches the transmitted PREAMBLE_INDEX has not beenreceived until an RAR window (e.g., ra-ResponseWindow configured by RRCsuch as RACH-ConfigCommon IE) expires. The wireless device may determinethat a random access response reception is not successful, for example,if a PDCCH addressed to the C-RNTI has not been received on the ServingCell where the preamble was transmitted until a RAR window for a beamfailure recovery procedure (e.g., ra-ResponseWindow configured inBeamFailureRecoveryConfig) expires.

A wireless device may determine the one or more retransmission of one ormore preambles, e.g., when the wireless device determines that acontention resolution is not successful. For example, the wirelessdevice may determine, based on Msg 3 1313 for four-step RA procedureand/or MsgB 1332 for two-step RA procedure, whether the contentionresolution is successful or not.

For example, a MAC entity of the wireless device may start a contentionresolution timer (e.g., ra-ContentionResolutionTimer) and may restartthe contention resolution timer (e.g., ra-ContentionResolutionTimer) ateach HARQ retransmission in the first symbol after the end of a Msg3transmission, for example, once a wireless device transmits, to a basestation, Msg3 1313. A wireless device may determine that a contentionresolution is not successful, for example, if the wireless device doesnot receive an indication of a contention resolution while a contentionresolution timer (e.g., ra-ContentionResolutionTimer) is running. Forexample, the wireless device may determine that a contention resolutionis not successful, for example, if the indication of the contentionresolution has not been received until the contention resolution timer(e.g., ra-ContentionResolutionTimer) expires. The wireless device maydiscard a TEMPRARY_C-RNTI indicated by an Msg2 1312 (or Msg B 1332)after or in response to an expiry of the contention resolution timer(and/or in response to a determination of the contention resolutionbeing unsuccessful).

For a two-step RA procedure, a wireless device may start a timer (e.g.,RAR window, MsgB window, or contention resolution timer), e.g., after orin response to transmitting Transport block 1342 comprising a contentionresolution identifier of the wireless device. The wireless device maydetermine that the one or more retransmission of MsgA 1331 (e.g.,Preambles 1341 and/or Transport block 1342), e.g., if at least one Msg Bcomprising the contention resolution identifier that the wireless devicetransmit has not been received until the timer expires. For example, fortwo-step RA procedure, a wireless device may fallback to four-step RAprocedure based on an explicit and/or implicit indication of MsgB. Forexample, if MsgB received by the wireless device comprises such explicitindication and/or an RNTI used for detecting a PDCCH scheduling the MsgBis a particular RNTI (e.g., RA-RNTI or msgB RNTI), the wireless devicemay determine to fall back to the four-step RA procedure. The wirelessdevice may transmit Msg3, e.g., after or in response to determining thefallback to the four-step RA procedure via resource(s) indicated by ULgrant in Msg B. In this case the wireless device may follow thefour-step RA procedure, e.g., starting the contention resolution timer,and/or determining whether the contention resolution is successful ornot. The wireless device may monitor a PDCCH while the contentionresolution timer (e.g., ra-ContentionResolutionTimer) is running. Thewireless device may restart the contention resolution timer (e.g.,ra-ContentionResolutionTimer) at each HARQ retransmission in the firstsymbol after the end of a Msg3 transmission. For example, the wirelessdevice may determine that a contention resolution is not successful, forexample, if the indication of the contention resolution has not beenreceived until the contention resolution timer (e.g.,ra-ContentionResolutionTimer) expires. The wireless device may discard aTEMPRARY_C-RNTI indicated by an Msg2 1312 (or Msg B 1332) after or inresponse to an expiry of the contention resolution timer (and/or inresponse to a determination of the contention resolution beingunsuccessful). The wireless device that determines the retransmissionduring a four-step RA procedure falling back from a two-step RAprocedure may perform a retransmission of MsgA 1331. The wireless devicethat determines the retransmission during a four-step RA procedurefalling back from a two-step RA procedure may perform a retransmissionof Msg1 1311. A wireless device may stop the contention resolution timerand determine that a contention resolution is successful, for example,if a notification of a reception of a PDCCH transmission of a cell(e.g., SpCell) is received from lower layers, and the wireless deviceidentifies that the PDCCH transmission is an indication of a contentionresolution corresponding to a Msg3 transmission (or MsgB transmission)that the wireless device performed.

A wireless device may maintain (e.g., increment) a counter counting anumber of preamble transmissions (e.g., PREAMBLE_TRANSMISSION_COUNTER)by a value of counter step (e.g., by 1), for example, after or inresponse to a random access response reception being unsuccessful and/orafter or in response to a contention resolution being unsuccessful. Thewireless device may determine that a random access procedure isunsuccessfully completed and/or a MAC entity of the wireless device mayindicate a random access problem to upper layer(s), for example, if thenumber of preamble transmissions may reach a predefined orsemi-statically configured value, (e.g., ifPREAMBLE_TRANSMISSION_COUNTER=preambleTransMax+1 where preambleTransMaxis the predefined or semi-statically configured value). The wirelessdevice may determine that a random access procedure is not completedand/or one or more retransmission of one or more Msg1 1311, Msg1 1321,or MsgA 1331 may be performed, for example, if the number of preambletransmissions does not reach the predefined or semi-staticallyconfigured value, (e.g., ifPREAMBLE_TRANSMISSION_COUNTER<preambleTransMax+1).

A wireless device may delay a particular period of time (e.g., a backofftime) for performing a retransmission of one or more Msg1 1311, Msg11321, or MsgA 1331. For example, the wireless device may set the backofftime to 0 ms, for example, when a random access procedure is initiated.The wireless device may set (or update) the backoff time based on thePREAMBLE_BACKOFF determined by a value in a BI field of the MAC subPDU(e.g., BI field in FIG. 19B). A value (or a bit string) in a BI fieldmay indicate a particular backoff time in a predefined orsemi-statically configured table. For example, the wireless device mayset the PREAMBLE_BACKOFF to a value indicated by the BI field of the MACsubPDU using the predefined or semi-statically configured table. Forexample, if the wireless device receives BI indicating index 3 (or 0010in a bit string), the wireless device may set the PREAMBLE_BACKOFF to avalue of row index 3 in the predefined or semi-statically configuredtable. For example, in FIG. 19B, the example format shows that four bitsare allocated for the BI fields. In this case, there may be 16 values(e.g., each of 16 values is identified by a particular row index) in thepredefined or semi-statically configured table. The wireless device mayset the PREAMBLE_BACKOFF to a value indicated by the BI field of the MACsubPDU multiplied with a scaling factor, (e.g., SCALING_FACTOR_BI), forexample, if the wireless device receives, from a base station, one ormore RRC messages indicating the scaling factor. The wireless device mayset (or update) the PREMABLE_BACKOFF based on a BI field, for example,if a downlink assignment has been received on the PDCCH for the RA-RNTIand the received TB is successfully decoded, and/or if the Random AccessResponse comprises a MAC subPDU with Backoff Indicator (BI in FIG. 19B).The wireless device may set the PREAMBLE_BACKOFF to 0 ms, for example,if a downlink assignment has not been received on the PDCCH for theRA-RNTI and/or the received TB is not successfully decoded, and/or ifthe Random Access Response does not comprise a MAC subPDU with BackoffIndicator (BI in FIG. 20B).

A wireless device may determine the backoff time, for example, if thewireless device determines that a random access response is notsuccessful and/or a contention resolution is not successful. Thewireless device may employ a particular selection mechanism to determinethe backoff time. For example, the wireless device may determine thebackoff time based on a uniform distribution between 0 and thePREAMBLE_BACKOFF. The wireless device may employ any type ofdistribution to select the backoff time based on the PREAMBLE_BACKOFF.The wireless device may ignore the PREAMBLE_BACKOFF (e.g., a value in BIfield in FIG. 20B) and/or may not have a backoff time. For example, thewireless device may determine whether to apply the backoff time to aretransmission of at least one preamble based on an event typeinitiating the random access procedure (e.g., Beam Failure Recoveryrequest, handover, etc.) and/or a type of the random access procedure(e.g., four-step or two-step RA and/or CBRA or CFRA). For example, thewireless device may apply the backoff time to the retransmission, forexample, if the random access procedure is CBRA (e.g., where a preambleis selected by a MAC entity of the wireless device) and/or if thewireless device determines that a random access procedure is notcompleted based on a random access response reception beingunsuccessful. For example, the wireless device may apply the backofftime to the retransmission, for example, if the wireless devicedetermines that a random access procedure is not completed based on acontention resolution being unsuccessful.

A wireless device may perform a random access resource selectionprocedure (e.g., select at least one SSB or CSI-RS and/or select PRACHcorresponding to at least one SSB or CSI-RS selected by the wirelessdevice), for example, if the random access procedure is not completed.The wireless device may delay the subsequent random access preambletransmission (e.g., or delay to perform a random access resourceselection procedure) by the backoff time.

A radio access technology may allow a wireless device to change (switch)a channel (a uplink carrier, BWP, and/or a subband) to transmit at leastone preamble for a retransmission. This may increase a number ofpreamble transmission opportunities in an unlicensed band. For example,a base station may transmit, to a wireless device, one or more messages(broadcast messages, and/or RRC messages) indicating a configuration ofthe one or more channels (e.g., uplink carrier, BWPs and/or subbands)that one or more PRACH are configured. A wireless device may select oneof the one or more channels (e.g., BWPs, and/or subbands) as a channel(e.g., a uplink carrier, BWP, and/or a subband) to transmit at least onefirst preamble. The wireless device may select the channel (e.g., uplinkcarrier, BWP, and/or subband) based on an LBT result. For example, thewireless device performs one or more LBTs on one or more channels, andselect the channel among the channel(s) being sensed as idle. Thewireless device may select the one of channels being sensed as idlebased on, for example, a random selection. There may be a case thatswitching a channel for a retransmission is not allowed (e.g., thisindication may be predefined or semi-statically informed).

A wireless device may determine the transmit power of the retransmissionof at least one preamble (or MsgA) based PREAMBLE_POWER_RAMPING_COUNTER.For example, the wireless device may set PREAMBLE_POWER_RAMPING_COUNTERto an initial value (e.g., 1) as an random access procedureinitialization. The MAC entity of the wireless device may, e.g., foreach Random Access Preamble and/or for each transmission of at least onepreamble transmitted, for example, after or in response to determining arandom access reception being unsuccessful and/or a contentionresolution being unsuccessful, increment PREAMBLE_POWER_RAMPING_COUNTERby a value of a counter step predefined or semi-statically configured bya base station. For example, The MAC entity of the wireless device mayincrement PREAMBLE_POWER_RAMPING_COUNTER by 1, e.g., ifPREAMBLE_TRANSMISSION_COUNTER is greater than one; if the notificationof suspending power ramping counter has not been received from lowerlayers (e.g., the notification is received in response to a preambletransmissions being dropped due to LBT failure and/or in response to aspatial filter is changed); and/or if SSB or CSI-RS selected is notchanged from the selection in the last Random Access Preambletransmission. The wireless device may determine a value ofDELTA_PREAMBLE based on a preamble format and/or numerology selected forthe random access procedure (e.g., one or more values of DELTA_PREAMBLEare predefined associated with one or more preamble format and/ornumerology. For a given preamble format and a numerology, the wirelessdevice may select a particular value of DELTA_PREAMBLE from the one ormore values.). The wireless device may determinePREAMBLE_RECEIVED_TARGET_POWER topreambleReceivedTargetPower+DELTA_PREAMBLE+(PREAMBLE_POWER_RAMPING_COUNTER−1)×PREAMBLE_POWER_RAMPING_STEP.The MAC layer of the wireless device may instruct the physical layer totransmit the Random Access Preamble based on a selected PRACH occasion,corresponding RA-RNTI (e.g., if available), PREAMBLE_INDEX and/orPREAMBLE_RECEIVED_TARGET_POWER.

For a two-step RA procedure, MsgA 1331 (or Transport Block 1342) maycomprise a common control channel (CCCH) SDU. For example, atransmission of the Transport Block 1342 is made for the CCCH logicalchannel. For example, the wireless device may transmit, to a basestation via the CCCH, an RRC (re)establishment request, an RRC setuprequest, and/or an RRC resume request. The wireless device may startmonitor a downlink control channel (e.g., a PDCCH) with the first RNTI(e.g., msgB RNTI). The received PDCCH via the downlink control channelindicates a downlink assignment of a PDSCH (e.g., MAC PDU) comprisingMsgB 1332. In this case, the MsgB 1332 (or the PDSCH (e.g., MAC PDU)comprising the MsgB1332) that the wireless device receives based on thedownlink assignment may comprise signalling radio bearer(s) (SRB(s)) RRCmessage(s). The SRB RRC message may comprise RRC (re)establishment, anRRC setup, and/or an RRC resume as responses of the RRC(re)establishment request, an RRC setup request, and/or an RRC resumerequest, respectively, that the wireless device transmits via MsgA 1331(or Transport Block 1342).

For the case that MsgA 1331 (or Transport Block 1342) comprises a commoncontrol channel (CCCH) SDU, an MAC PDU (or a PDSCH) may multiplex one ormore MsgBs for one or more wireless devices. The MAC PDU may multiplexone or more MsgBs indicating a success of MsgA only. The MAC PDU maymultiplex one or more MsgBs indicating a failure (e.g., fallbackresponse) of MsgA only. The MAC PDU may multiplex a plurality of MsgBscomprising one or more responses indicating a success of MsgA and/or oneor more responses indicating a failure of MsgA (e.g., fallback RAR). TheMAC PDU may comprise at least one Backoff Indication. For a MsgBindicating a success of MsgA, the MsgB may comprise at least one offollowing: a contention resolution identifier (that is matched to anidentifier that the wireless device transmit via MsgA), a C-RNTI, and/ora TA command. For a MsgB indicating a failure of MsgA (e.g., fallbackRAR), the MsgB may comprise at least one of following: an RAPID, a ULgrant (e.g., to retransmit the MsgA payload), a TC-RNTI, and/or TAcommand. For example, upon receiving the MsgB indicating a failure ofMsgA (e.g., fallback RAR), the wireless device may proceed to Msg3 1313transmission of four-step RACH procedure (e.g., in FIG. 13A). Forexample, the Msg3 1313 that the wireless device transmit as a part offallback procedure, comprises the CCCH SDU transmitted via MsgA. The MACPDU comprising a MsgB indicating a success of MsgA may not bemultiplexed with a four-step RACH RAR (e.g., Msg 2 1312).

FIG. 23 is an example diagram illustrating a two-step RA procedureperformed between a wireless device and a base station as per an aspectof an example embodiment of the present disclosure. As shown in FIG. 23, the wireless device may transmit a MsgA comprising a firsttransmission of a preamble and a second transmission of a transportblock. The transport block may comprise a CCCH SDU. The CCCH SDU maycomprise an RRC (re)establishment request, an RRC setup request, and/oran RRC resume request. The wireless device may start to monitor adownlink control channel addressed to a particular RNTI. The wirelessdevice may start a MsgB RAR window after or in response to transmittingthe MsgA or the transport block. The particular RNTI may be referred toas msgB-RNTI or a RA-RNTI. The wireless device may determine theparticular RNTI based on the timing (e.g., OFDM symbol, slot, subframe,and/or SFN numbers) and/or frequency indices of radio resources of thefirst transmission for the preamble and/or the second transmission forthe transport block. The wireless device may determine the particularRNTI further based on a preamble index of the preamble and/or a DMRSport index.

The wireless device may detect and/or receive a PDCCH addressed to theparticular RNTI during the MsgB RAR window. A DCI received via the PDCCHmay comprise a downlink assignment that indicates a PDSCH reception. TheDCI may be a particular DCI whose format is predefined. For example, theDCI may be a DCI format 1_0 or DCI format 1_1. The wireless device mayreceive and/or decode the PDSCH based on the downlink assignment. Thephysical layer may decode the PDSCH and send the decoded data to the MACentity in the form of a MAC PDU. The wireless device may identify aresponse (e.g., a MsgB) to the MsgA in the MAC PDU. The response to theMsgA may comprise a preamble identifier that matches the preambleidentifier of the preamble that the wireless device transmitted to thebase station via the MsgA. The response to the MsgA may comprise anexplicit or implicit indicator that indicates a success RAR or afallback RAR. For example, the response to the MsgA may comprise a fieldindicating a type (success or fallback) of RAR. The wireless device mayidentify the type of RAR based on a format of the received RAR. Forexample, the success RAR and the fallback RAR may comprise one or moredifferent types and/or sizes of fields based on which the wirelessdevice may identify the type of RAR.

For a two-step RA procedure, like the two-step RA procedure in FIG. 23 ,a wireless device may determine, at least based on a C-RNTI, whether acontention resolution is successful or not and/or whether a MsgB isreceived successfully or not. The wireless device may transmit a MsgAcomprising a C-RNTI to a base station if the wireless device already hasan assigned C-RNTI. For example, the wireless device may have received amessage comprising the C-RNTI from the base station prior totransmission of the MsgA. The MsgA (or a transport block of the MsgA)may comprise a C-RNTI MAC CE indicating the C-RNTI to the base station.The wireless device may start to monitor a downlink control channel fora Msg B with one or more RNTIs, e.g., after or in response totransmitting the MsgA (or a transport block of Msg A). For example, thewireless device may monitor a downlink control channel (e.g., PDCCH)with one or more RNTIs, after or in response to transmitting the MsgAindicating the C-RNTI (e.g., C-RNTI MAC CE). The one or more RNTIs maycomprise a first RNTI (e.g., MsgB-RNTI) determined (or calculated) basedon uplink radio resources used for the MsgA transmission. For example,the first RNTI may be an RA-RNTI. For example, the first RNTI maydetermine based on uplink radio resources used for a Preamble and/ortransport block of the Msg A. The uplink radio resources may comprisetime (e.g., in terms of any combination of OFDM symbol, slot number,subframe number, and/or SFN) and/or frequency indexes of a PRACHoccasion for transmission of the MsgA preamble), a preamble identifierof the MsgA preamble, time (e.g., in terms of any combination of OFDMsymbol, slot number, subframe number, SFN, and/or time offset withrespect to associated PRACH occasion) and/or frequency indexes a PUSCHoccasion for transmission of the MsgA transport block, and/or DMRSindex(es) (e.g., DMRS port identifier(s)) of the PUSCH occasion fortransmission of MsgA transport block). For example, the wireless devicemay monitor PDCCH(s) addressed to the C-RNTI for a success response theMsgA and monitor PDCCH(s) addressed to the first RNTI (e.g., msgB-RNTI)for a failure (or fallback) response to the MsgA. The wireless devicemay start a timer (e.g., contention resolution timer) and/or monitor adownlink control channel while the timer is running. For example, thetimer may determine how long (e.g., for a particular time interval or aperiod of time) the wireless device monitors the downlink controlchannel to receive a response (e.g., a success response and/or afallback response) to the MsgA from the base station.

The wireless device may stop monitoring the downlink channel if thewireless device receives at least one response, e.g., a PDCCH addressedto the C-RNTI and/or a PDCCH addressed to the first RNTI). The wirelessdevice may determine that a contention resolution is successful based onone or more conditions. For example, the wireless device may determinethat a contention resolution is successful if a PDCCH addressed to theC-RNTI included in the MsgA is detected, and a PDSCH indicated by thePDCCH (e.g., via a downlink assignment of a DCI) comprises a TA command.For example, the wireless device may determine that a contentionresolution is successful if a PDCCH addressed to the C-RNTI included inthe MsgA is detected, and a PDSCH indicated by the PDCCH (e.g., via adownlink assignment of a DCI) comprises a UL grant (e.g., if thewireless device is already synchronized). The PDCCH addressed to theC-RNTI may be an indication of a success response. For example, thewireless device stops monitoring for a PDCCH addressed to the C-RNTI ifthe wireless device receives a fallback response (e.g., RAR). In thiscase, the contention resolution is not successful, and the wirelessdevice may fall back to Msg3 (e.g., as discussed above in FIG. 13 )transmission based on fallback operation. The wireless device mayidentify the fallback response based on a PDCCH addressed to the firstRNTI (e.g., MsgB RNTI). For example, while the wireless device monitorsthe PDCCH, the wireless device detects the PDCCH addressed to the firstRNTI (e.g., msgB RNTI). The PDCCH (e.g., DCI with a downlink assignment)may comprise a downlink assignment based on which the wireless devicereceives a PDSCH comprising the fallback response. The PDSCH maycomprise one or more responses. The wireless device identifies aresponse from the one or more responses based on one or moreidentifiers. For example, the wireless device identifies a response fromthe one or more responses if an identifier of the response is matched toa preamble index of the MsgA preamble. The response may comprise an ULgrant indicating uplink radio resource(s) where the wireless devicetransmits the Msg3 based on the fallback operation. FIG. 19A (e.g. withFIG. 19B and FIG. 19C) illustrates an example format of a PDU of thePDSCH received based on the first RNTI. For example, RAPID in FIG. 19Cis an example identifier based on which the wireless device identifiesits corresponding response (e.g., MAC RAR in FIG. 19A) for a fallbackresponse. The wireless device may determine MsgB reception (orcontention resolution or MsgA transmission attempt) is failed if neitherfallback response nor PDCCH addressed C-RNTI is detected within thetimer (e.g., contention resolution timer). The wireless device, in thiscase, may perform a back off operation based on the backoff indicator(e.g., FIG. 19B) if received in the MsgB.

FIG. 24 is an example diagram illustrating a two-step RA procedureperformed between a wireless device and a base station as per an aspectof an example embodiment of the present disclosure. Although not shownin FIG. 24 , the wireless device may receive a message comprising aC-RNTI from the base station prior to performing the two-step RAprocedure. The wireless device may transmit the C-RNTI (e.g., C-RNTI MACCE indicating the C-RNTI) to the base station via a MsgA during thetwo-step RA procedure. For example, during the two-step RA procedure,the wireless device may transmit the MsgA comprising a firsttransmission of a preamble and a second transmission of a transportblock. The transport block may comprise the C-RNTI (e.g., C-RNTI MAC CEindicating the C-RNTI). The wireless device may start to monitor adownlink control channel with a plurality of RNTIs. The plurality ofRNTIs may comprise the C-RNTI. The plurality of RNTIs may comprise aMsgB-RNTI. The plurality of RNTIs may comprise an RA-RNTI. The wirelessdevice may determine a MsgB-RNTI and/or RA-RNTI based on the timing(e.g., OFDM symbol, slot, subframe, and/or SFN numbers) and/or frequencyindices of radio resources of the first transmission for the preambleand/or the second transmission for the transport block. The wirelessdevice may determine the particular RNTI further based on a preambleindex of the preamble and/or a DMRS port index. The wireless device maystart a MsgB RAR window after or in response to transmitting the MsgA(or the transport block). The wireless device may monitor the downlinkcontrol channel during the MsgB RAR window. The wireless device may stopmonitoring the downlink control channel if the wireless device receives,via the downlink control channel during the MsgB RAR window, at leastone PDCCH addressed to the C-RNTI and/or MsgB-RNTI (or RA-RNTI).

FIG. 25A and FIG. 25B are example diagrams illustrating two-step RAprocedures performed between a wireless device and a base station as peran aspect of an example embodiment of the present disclosure. Althoughnot shown in FIG. 25A or FIG. 25B, the wireless device may receive amessage comprising a C-RNTI from the base station prior to performingthe two-step RA procedure The wireless device may transmit the C-RNTI(e.g., C-RNTI MAC CE indicating the C-RNTI) to the base station via aMsgA during the two-step RA procedure. The wireless device may start aMsgB RAR window after or in response to transmitting the MsgA (or thetransport block). The wireless device may monitor the downlink controlchannel during the MsgB RAR window. The wireless device may monitor thedownlink control channel with C-RNTI and/or a MsgB-RNTI (or RA-RNTI).The wireless device may stop monitoring the downlink control channel ifthe wireless device receives, via the downlink control channel duringthe MsgB RAR window, at least one PDCCH addressed to the C-RNTI and/orMsgB-RNTI (or RA-RNTI).

FIG. 25A is an example diagram illustrating that the wireless devicereceives, via the downlink control channel, a PDCCH addressed to theC-RNTI of the wireless device. The wireless device, which transmits theC-RNTI (e.g., C-RNTI MAC CE indicating the C-RNTI) via the MsgA, maymonitor a downlink control channel with C-RNTI and/or MsgB-RNTI (orRA-RNTI). The wireless device may stop monitoring the downlink controlchannel with the C-RNTI and/or MsgB-RNTI (or RA-RNTI) after or inresponse to receiving the PDCCH addressed to the C-RNTI. The detectedPDCCH may comprise a DCI comprising a downlink assignment based on whichthe wireless device may receive a PDSCH (e.g., MAC PDU). The receivedPDSCH (or MAC PDU) may comprise a TA command (e.g., TA command MAC CE).The wireless device may stop monitoring the downlink control channelwith the C-RNTI and/or msgB-RNTI (or RA-RNTI) after or in response toreceiving the PDCCH addressed to the C-RNTI and/or the correspondingPDSCH (or MAC CE) comprising the TA command. In this case, the wirelessdevice may determine that the two-step RA procedure completessuccessfully, a reception of MsgB is successful, and/or a contentionresolution completes successfully.

FIG. 25B is an example diagram illustrating that the wireless devicereceives, via the downlink control channel, a PDCCH addressed to theMsgB-RNTI (or RA-RNTI). The wireless device, which transmits the C-RNTI(e.g., C-RNTI MAC CE indicating the C-RNTI) via the MsgA, may monitor adownlink control channel with the C-RNTI and/or MsgB-RNTI (or RA-RNTI).The wireless device may stop monitoring the downlink control channelwith the C-RNTI and/or MsgB-RNTI (or RA-RNTI) after or in response toreceiving the PDCCH addressed to msgB-RNTI (or RA-RNTI). The detectedPDCCH may comprise a DCI indicating a downlink assignment based on whichthe wireless device may receive a PDSCH (e.g., MAC PDU). The receivedPDSCH (or MAC PDU) may comprise one or more RARs (e.g., one or moreMsgBs). The wireless device may stop monitoring the downlink controlchannel with the C-RNTI and/or msgB-RNTI (or RA-RNTI) after or inresponse to receiving the PDCCH addressed to C-RNTI and/or thecorresponding PDSCH (or MAC PDU) comprising the one or more RARs (e.g.,one or more MsgBs). The wireless device may identify an RAR (e.g., MsgB)corresponding to the MsgA based on a preamble identifier matched to apreamble identifier of the preamble transmitted by the wireless devicein the MsgA. For example, the RAR (e.g., MsgB) may comprise at least onepreamble identifier. The wireless device may determine that an RAR(e.g., MsgB) in the PDSCH (or MAC PDU) corresponds to the MsgA if apreamble identifier of the RAR (e.g., MsgB) matches to the preambleidentifier of the preamble that the wireless device transmits to thebase station via the MsgA. The wireless device may stop monitoring thedownlink control channel with the C-RNTI and/or msgB-RNTI (or RA-RNTI)after or in response to identifying the RAR (e.g., MsgB) from the PDSCH(or MAC PDU) based on the preamble identifier. The RAR may indicate afallback to a Msg3 transmission of a four-step RA procedure. Forexample, the RAR may comprise a UL grant and a TA command. The wirelessdevice may transmit the Msg3 via radio resource(s) indicated by the ULgrant with a UL transmission timing adjusted based on the TA command.The Msg3 may comprise at least a portion of transport block. Forexample, the Msg3 and the transport block may be the same. For example,the Msg3 may comprise the C-RNTI.

In a two-step RA procedure, a wireless device may transmit a C-RNTI(e.g., C-RNTI MAC CE indicating the C-RNTI) to a base station via atransmission of MsgA comprising a first transmission of a preamble and asecond transmission of a transport block. For example, the transportblock may comprise the C-RNTI (e.g., C-RNTI MAC CE indicating theC-RNTI). The wireless device may start to monitor a downlink controlchannel after or in response to transmitting the MsgA. For example, thewireless device may start a window (e.g., MsgB RAR window) after or inresponse to transmitting the MsgA (e.g., the transport block) andmonitor the downlink control channel for a response of the MsgA duringthe window (e.g., MsgB RAR window). The wireless device may receiveand/or detect, via the downlink control channel during the window, aPDCCH addressed to C-RNTI. The PDCCH may comprise a DCI indicating adownlink assignment of PDSCH. The wireless device may attempt to receiveand/or decode the PDSCH based on the downlink assignment. The downlinkassignment may indicate parameters based on which the wireless devicereceives the PDSCH. For example, the downlink assignment may indicate atleast one of following: a frequency domain resource assignment indicator(e.g., in terms of one or more frequency offsets), a time domainresource assignment indicator (e.g., in terms of OFDM symbol and/or slotoffsets from a reception timing of the PDCCH, and/or duration of thePDSCH transmission), modulation and coding scheme, redundancy versionindicator, a downlink assignment index, PUCCH resource indicator forACK/NACK transmission of a reception of the PDSCH, transmit powercontrol command of scheduled PUCCH for the ACK/NACK transmission,PDSCH-to HARQ feedback (e.g., the ACK/NACK transmission) timingindicator.

There may be a case where the wireless device successfully receives(and/or detects) the PDCCH addressed to the C-RNTI that wireless devicetransmits to the base station but fails to decode the PDSCH receivedbased on the downlink assignment. The problem in this case is that thewireless device may not transmit a negative acknowledgement (NACK)(e.g., NACK indication using UCI) to the base station if the PDSCH (orMAC PDU) comprises a TA command and/or a valid TA value is not availableto the wireless device. For example, the wireless device may nottransmit a NACK indication (e.g., using UCI) of a reception of the PDSCHto the base station if a TA timer of the wireless device expires. The TAtimer of the wireless device may start (or restart) after or in responseto receiving a TA command prior to the transmission of the MsgA. Thewireless device may not transmit a NACK indication (e.g., using UCI) ofa reception of the PDSCH to the base station, if no TA value has beenreceived or the TA timer is not running or expired. This may be a casethat the wireless device cannot transmit a transport block (or packet,PUSCH) or a control signal (e.g., UCI and/or PUCCH) to the base stationafter or in response to determining (or identifying), based on detectinga PDCCH addressed to C-RNTI, that a contention resolution is successful(or the base station received Msg A successfully).

FIG. 26 is an example diagram of a RA procedure as per an aspect of anexample embodiment of the present disclosure. The wireless device mayperform (or initiate) an RA procedure (e.g., a four-step RA procedure).The wireless device may transmit Preamble (e.g., Msg 1 1311). Thewireless device may monitor control channel for DCIs scrambled byRA-RNTI. The wireless device may receive a random access response (e.g.,PDSCH and/or Msg2 1312) corresponding to the Preamble (e.g., Msg1 1311).In an example, the wireless device may fail to decode the response. Thewireless device that fails to decode the response (e.g., PDSCH and/orMsg2 1312) may retransmit a preamble. In an example, the wireless devicemay successfully decode the random access response (e.g., PDSCH and/orMsg2 1312). The response may comprise one or more fields indicating a TAvalue. The wireless device may adjust (or determine), based on the TAvalue, a UL transmission timing. For example, a base station maydetermine the TA value based on a reception timing of received Preamble(Msg1 1311) (e.g., by comparing the reception timing of the receivedPreamble at the base station and a scheduled transmission timing of thereceived Preamble at the wireless device). The wireless device maytransmit C-RNTI (e.g., C-RNTI MAC CE), if received from the basestation, via Msg3 1313. The wireless device may receive, via a downlinkcontrol channel, a PDCCH addressed to the C-RNTI. The wireless devicemay determine a contention resolution successful after or in response toreceiving the PDCCH addressed to the C-RNTI. The wireless device maydetermine that the initiated RA procedure is complete successfullyand/or a contention resolution is successful, e.g., after or in responseto detecting the PDCCH addressed to the C-RNTI. The PDCCH may compriseDCI. The wireless device may receive a PDSCH (e.g., Msg4 1314) based ona downlink assignment indicated by the DCI in the PDCCH. The wirelessdevice may fail to decode the PDSCH (e.g., Msg4 1314). The wirelessdevice may transmit an NACK of a reception of Msg4 (e.g., indication offailure of decoding the PDSCH (Msg4)). The wireless device may determinea UL transmission timing of the NACK based on the TA value indicated bythe Msg2 1312. For example, the four-step RA procedure may provide avalid TA value to the wireless device, e.g., if the wireless deviceperform Msg4. The wireless device may determine (e.g., expect) thatthere is one PDCCH addressed to the C-RNTI transmission (and/or a PDSCHtransmission scheduled by the one PDCCH) from the base station during awindow started (e.g., while a timer is running, the timer started),after or in response to transmitting the MsgA (or Transport block).

In a two-step RA procedure, the wireless device may transmit an MsgAcomprising a transport block that indicates a C-RNTI of the wirelessdevice. In this case, the wireless device may determine a random accessresponse (e.g., PDSCH) to the MsgA at least based on whether a PDCCHthat schedules the random access response (e.g. PDSCH) is addressed tothe C-RNTI or not. For example, the wireless device may determine thatthe two-step RA procedure successfully completes, e.g., if the wirelessdevice receives the PDCCH addressed to the C-RNTI and/or if the wirelessdevice receives (e.g., successfully decode) the random access response(e.g., scheduled by the PDCCH).

In existing technologies, if the wireless device fails to decode therandom access response (e.g., PDSCH) in a two-step RA procedure, thewireless device may determine a retransmission of MsgA or Msg1 of atwo-step RA procedure. It may be inefficient to determine theretransmission. The retransmission of MsgA or Msg1 determined based onfailing to decode the PDSCH may increase a latency of the two-step RAprocedure. For example, the retransmission may require the wirelessdevice to wait for a next available PRACH and/or PUSCH for theretransmission. The retransmission of the MsgA or Msg1 may increase acongestion level of a PRACH and/or PUSCH in a network, which, in turn,may increase the likelihood that a collision occurs during theretransmission with other wireless device(s). There is a need to enhancea mechanism for wireless device and base station procedures, e.g., whenthe wireless device fails to decode a random access response (e.g.,PDSCH) scheduled by a PDCCH addressed to a C-RNTI of the wireless deviceduring the two-step RA procedure.

Example embodiments implements enhanced two-step RA procedures to reducedelay and congestion level, for example, when the random access responseis not successfully decoded. In example embodiment(s), the wirelessdevice may selectively determine when and/or whether to retransmit MsgA,e.g., based on whether a valid TA is available or not. For example, thewireless device may have a valid TA (e.g., TA timer is running), may bea close proximity of a base station, where no TA is needed (e.g., TA=0),or may be in a small cell where no a TA is needed for uplinktransmission (e.g., TA=0). In this case, the wireless device transmits,via PUCCH indicated by a PDCCH, an NACK that is an indication of failureof decoding a PDSCH scheduled by the PDCCH. The PUCCH may be a channeldedicated to the wireless device. Transmission (e.g., the NACK) via adedicated channel (e.g., PUCCH) provides a better performance (e.g., ahigher success rate of uplink transmission) than the one (e.g., MsgA)via a shared channel (e.g., the PRACH and/or PUSCH for MsgA) due to thecontention occurred in the shared channel. A wireless device, e.g., thathas an invalid TA (e.g., TA timer expires), may be located cell edgearea, where an adjustment of an uplink transmission timing is required,or may be in a large (or macro) cell where a TA is needed for adjustingan uplink transmission timing. In this case, the wireless device maydetermine a retransmission of MsgA, after or in response to decodingfailure of the PDSCH scheduled by the PDCCH addressed to C-RNTI of thewireless device. The wireless device that needs uplink transmissiontiming adjustment may have one or more additional opportunities toreceive one or more PDSCH (e.g., MsgB) based on adjusting (or extending)a timer or a window (e.g., based on example embodiments disclosed inthis specification) to monitor a downlink control channel and/or for theone or more PDSCH (e.g., MsgB). The determination based on whether thevalid TA is available may provide a proper selection for the wirelessdevice to correct a reception of PDSCH that the wireless device fails todecode. Example embodiments improves uplink transmission efficienciesfor two-step RA procedures. As unlike a four-step RA procedure, anuplink transport block comprising a wireless device identifier (e.g.,C-RNTI) and a preamble are transmitted in the first step (e.g., MsgAtransmission) of the RACH procedure. For example, if the wireless devicetransmits ACK/NACK regardless of TA value, the wireless device and basestation need to implement a more complex uplink control channel formatand uplink transmission procedure enabling ACK/NACK transmission in theuplink. In an example embodiment, a base station receiving MagA maydetermine the wireless device identifier. The base station may determinea C-RNTI based on the wireless device identifier and may transmit arandom access response using C-RNTI dedicated to the wireless device.The proper selection in example embodiment(s) may reduce delay,signaling overhead and/or avoid unnecessary battery power consumptionfor the wireless device.

In an example, a wireless device may initiate a two-step RA procedure.The wireless device may transmit an MsgA comprising a preamble and atransport block. For example, the transport block may comprise a C-RNTIMAC CE indicating a C-RNTI of the wireless device. The wireless devicethat transmits the C-RNTI (e.g., C-RNTI MAC CE) via the MsgA (orTransport block of the MsgA) may fail to decode a PDSCH comprising aresponse (MsgB) to the MsgA. In this case, the wireless device mayselectively select whether to retransmit MsgA (and/or Msg1) or totransmit a PUCCH (NACK) indicating a decoding failure of the response(the PDSCH or MsgB) to the MsgA. For example, the wireless devicedetermines to transmit the PUCCH scheduled (indicated) by a PDCCHscheduling the PDSCH, e.g., if the wireless device determines no TA(e.g., no uplink transmission timing adjustment) is needed to transmitthe PUCCH or a current TA is valid (e.g., TA timer is running) to beused for a transmission of the PUCCH. For example, the wireless devicedetermines to retransmit MsgA, e.g., if the wireless device determinesthat a new or updated TA (e.g., uplink transmission timing adjustment)is needed to transmit the PUCCH. The wireless device may determinewhether to transmit the PUCCH or not based on one or more ways. Thewireless device determines whether to transmit the PUCCH or not based ona TA timer. For example, the wireless device determines that a new orupdated TA (e.g., uplink transmission timing adjustment) is needed,e.g., if a TA timer expires. In this case, the wireless device maydetermine to retransmit MsgA. For example, the wireless devicedetermines to transmit the PUCCH, e.g., if a TA timer is running. Inthis case, the wireless device may determine to transmit the PUCCH withan uplink transmission timing adjusted a current TA value. For example,the wireless device determines to transmit the PUCCH, e.g., if no TA(e.g., no uplink transmission timing adjustment) is needed to transmitthe PUCCH. For example, SIB or RRC message, received by the wirelessdevice from a base station, may indicate no TA is needed by an explicitor implicit indicator. For example, the explicit or implicit indicatoris a small cell indicator. In this case, the wireless device maydetermine to transmit the PUCCH (e.g., with a TA value set to zero or avalue semi-statically configured by the SIB or the RRC). Thedetermination whether to retransmit an MsgA (or Msg1) or transmit PUCCHin example embodiment(s) may reduce a signaling overhead, battery powerconsumption, and/or the likelihood that a collision occurs during theretransmission with other wireless device(s).

In example embodiment(s), the wireless device determines whether totransmit the PUCCH or not based on a measure received signal strength ofa downlink reference signal (e.g., pathloss reference signal). Forexample, the measure received signal strength indicates a distancebetween the wireless device and the base station. For example, SIB orRRC message(s), received by the wireless device from a base station, mayindicate a power value based on which the wireless device determineswhether the wireless device is located in a close proximity of the basestation. For example, the wireless device determines to transmit PUCCH,e.g., if the measure received signal strength exceeds the power value.For example, the wireless device determines to retransmit MsgA, e.g., ifthe measure received signal strength smaller than or equal to the powervalue.

FIG. 31 is an example diagram of PUCCH and/or MsgA transmission as peran aspect of an example embodiment of the present disclosure. Thewireless device initiating a two-step RA procedure may transmit MsgA1331 comprising Preamble 1341 and Transport block 1342. The MsgA 1331(or Transport block 1342) may indicate C-RNTI of the wireless device (orcomprise C-RNTI MAC CE indicating the C-RNTI of the wireless device).The wireless device may start to monitor a downlink control channel fora response (MsgB) to the MsgA during a time interval, e.g., in responseto transmitting MsgA 1331 (or Transport block 1342). For example, thetime interval may be implemented by a timer started in response totransmitting MsgA 1331 (or Transport block 1342). For example, the timeinterval may be implemented by a window, e.g., MsgB RAR window as shownin FIG. 31 , started in response to transmitting MsgA 1331 (or Transportblock 1342). The wireless device may detect a PDCCH addressed to theC-RNTI. The PDCCH may comprise a DCI indicating a downlink assignment ofa PDSCH (a response, e.g., MsgB, of the MsgA). The DCI may furtherindicate a time/frequency radio resource of PUCCH where the wirelessdevice transmits ACK or NACK as an indication of decoding success orfailure of the PDSCH. The PDSCH (a response, e.g., MsgB, to the MsgA)may comprise a new or updated TA. The wireless device may fail to decodethe PDSCH. The wireless device may determine to transmits the PUCCH,e.g., if no TA (e.g., TA=0) is needed to transmit the PUCCH and/or acurrent TA is valid (e.g., TA timer is running) to be used for uplinktransmission timing adjustment of the PUCCH. The wireless device may notbe able to transmits the PUCCH, e.g., if a new or updated TA is neededto transmit the PUCCH (e.g., TA timer expires) to be used for uplinktransmission timing adjustment of the PUCCH. The wireless device mayhave one or more additional opportunities to receive one or more PDSCHsbased on a timer or window adjustment (or extension) disclosed byexample embodiments in this specification (e.g., FIG. 27A, FIG. 27B,FIG. 28A, FIG. 28B, FIG. 29 , and/or FIG. 30 ). The wireless device maydetermine to retransmit MsgA, e.g., if a TA timer expires (e.g., novalid TA value is available).

For example, a wireless device may transmit a first message comprising afirst preamble and a first transport block comprising a wireless deviceidentifier. The wireless device may receive, via a downlink controlchannel, a first downlink control information addressed to the wirelessdevice identifier. The wireless device may determine a decoding failureof a first response received based on the first downlink controlinformation. The wireless device may, based on the determination of thedecoding failure and/or whether a valid timing advance value isavailable for transmitting an uplink control signal, transmit: a secondmessage comprising a second preamble and a second transport block; or anuplink control signal.

For example, a wireless device may transmit a first message comprising afirst preamble and a first transport block comprising a wireless deviceidentifier. The wireless device may receive, via downlink controlchannel, a first downlink control information addressed to the wirelessdevice identifier. The wireless device may determine a decoding failureof a first response received based on the first downlink controlinformation. The wireless device may determine whether a valid timingadvance value is available for transmitting an uplink control signal.The wireless device may, based on the determining whether a valid timingadvance value is available, selecting one of: a second messagecomprising a second preamble and a second transport block; or uplinkcontrol signal. The wireless device may transmit a selected one.

FIG. 32 is an example flow diagram of a wireless device as per an aspectof an example embodiment of the present disclosure. The wireless devicemay transmit a first preamble via a cell. The wireless device mayreceive a downlink grant for a random access response. The wirelessdevice may determine a failure to receive the random access response.The wireless device may determine, based on the failure and a timealignment timer of the cell, an uplink signal for transmission via thecell, wherein the uplink signal is one of a second preamble and anegative acknowledgement.

FIG. 33 is an example flow diagram of a base station as per an aspect ofan example embodiment of the present disclosure. The base station mayreceive a first preamble via a cell. The base station may transmit adownlink grant for a random access response. The base station mayreceive an uplink signal. For example, the uplink signal comprises,based on a failure to transmit the random access response and a timealignment timer of the cell, one of a second preamble and a negativeacknowledgement.

Example embodiments of the present disclosure may improve adetermination of the retransmission of MsgA. In an example, a basestation may not transmit, to a wireless device, a PDCCH addressed toC-RNTI, e.g., if the base station does not receive and/or decode MsgA(e.g., Transport Block) comprising the C-RNTI (e.g., C-RNTI MAC CE). Abase station may transmit, to a wireless device, a PDCCH addressed toC-RNTI, e.g., if the base station successfully receives and/or decodesMsgA (e.g., Transport Block) comprising the C-RNTI (e.g., C-RNTI MACCE). The wireless device that detects a PDCCH addressed to C-RNTI andfails to decode a PDSCH based on a downlink assignment indicated by aDCI of the PDCCH may determine that the base station successfullyreceives the MsgA. In this case, the wireless device may determine thatthe PDSCH is transmitted from the base station to the wireless device(e.g., not to any other wireless device(s)), e.g., determine acontention resolution successful. In this case, retransmission of thePDSCH from the base station may improve increased latency and congestionlevel over the existing technologies. For example, the wireless devicemay keep (or continue) monitoring for another PDSCH, after or inresponse to a determination of failing to decode a PDSCH based on adownlink assignment indicated by the DCI of the PDCCH detected based onC-RNTI. The base station may determine that the wireless device may failto decode the transmitted PDSCH, e.g., if the base state does notreceive a PUCCH (e.g., ACK or NACK) scheduled by the downlink assignmentin the PDCCH. The base station may transmit the PDSCH, e.g., after or inresponse to a determination that the wireless device fails to decode thetransmitted PDSCH. For example, the base station transmits, to thewireless device, a second PDCCH comprising a second downlink assignmentto indicate, to the wireless device, a transmission of a second PDSCH,e.g., after or in response to the determination that the wireless devicefails to decode the transmitted PDSCH. The base station may transmit, tothe wireless device, the second PDSCH based on the second downlinkassignment, e.g., after or in response to transmitting the second PDCCH.Example embodiments may provide a way, for the wireless device, tomonitor the another PDSCH with enhanced timer or window management.Example embodiments may enhance a determination of the retransmission ofMsgA based on the enhanced timer or window management. Exampleembodiments may provide an improved determination, for the base station,whether another PDSCH needs to be transmitted to the wireless device ornot.

In the example embodiments in this specification, the wireless devicemay not have received a TA value from a base station and/or may not havea valid TA (e.g., TA timer expires), e.g., before transmitting MsgAand/or before receiving MsgB. For example, the wireless device may set aTA value to zero, for an uplink transmission of MsgA (e.g., Preamble1341 and/or Transport block 1342). The wireless device in the exampleembodiments in this specification may initiate a two-step RA procedurewithout a valid TA or with no TA. This wireless device may transmit, asshown in FIG. 25A, C-RNTI via MsgA and receive a PDCCH addressed to theC-RNTI. This wireless device may successfully detect the PDCCH addressedto the C-RNTI and may fail to decode a PDSCH received based on adownlink assignment indicated by a DCI in the PDCCH. In this case, thewireless device may not transmit an NACK of a reception of PDSCH (e.g.,MsgB) to the base station, e.g., since the wireless device has no validTA. For example, a new or updated TA value, as described in FIG. 25A,may be contained in the PDSCH which the wireless device fails to decode(e.g., fails to acquire the new or updated TA value due to a decodingfailure of the PDSCH). This wireless device may determine aretransmission of MsgA (e.g., the MsgB RAR window in FIG. 25A expires)in this case, e.g., where the contention resolution is resolved based on(or by) detecting the PDCCH addressed to the C-RNTI. This wirelessdevice may not determine that the initiated two-step RA procedure iscomplete successfully after or in response to detecting the PDCCHaddressed to the C-RNTI.

In an example, a wireless device, that detects a PDCCH addressed C-RNTIand fails to decode PDSCH received based on a downlink assignmentindicated by the PDCCH, may continue to monitor (or keep monitoring) thedownlink control channel. For example, the wireless device determineswhether the PDSCH is successfully decoded or not base on a cyclicredundancy check (CRC) result (decoding success or failure) for thePDSCH. For example, the wireless device continues to monitor (or keepsmonitoring) the downlink control channel, e.g., if a timer started afteror in response to MsgA (or Transport block) transmission is running (orduring a window (e.g., msgB RAR window) started after or in response toMsgA (or Transport block) transmission). The wireless device maydetermine (e.g., expect) that there are one or more PDCCHs addressed tothe C-RNTI (and/or one or more PDSCHs scheduled by the one or morePDCCHs) from the base station during the window started (e.g., while thetimer is running, the timer started), after or in response totransmitting the MsgA (or Transport block). The wireless device mayreceive a second PDCCH comprising a second DCI indicating a seconddownlink assignment. The wireless device may receive a second PDSCH(e.g., MsgB) using the second downlink assignment. The wireless devicemay decode the second PDSCH successfully. The second PDSCH may comprisea response (e.g., MsgB) of the MsgA. The response may indicate a TAvalue (e.g., indicated by a TA command). For example, the TA value isindicated by a TA command MAC CE. The wireless device may transmit anACK (e.g., using UCI) of a reception of MsgB to the base station, e.g.,after or in response to decoding the second PDSCH (e.g., MsgB)successfully. The uplink transmission of the ACK may be indicated(and/or scheduled) by the second PDCCH. For example, the second downlinkassignment may comprise a resource indicator of a PUCCH for ACK/NACKtransmission of a reception of the PDSCH, a transmit power controlcommand of the PUCCH for the ACK/NACK transmission, PDSCH-to-HARQfeedback (e.g., the ACK/NACK transmission) timing indicator. Thewireless device may attempt to decode one or more PDSCHs scheduled(and/or indicated) by one or more PDCCHs addressed to C-RNTI during thewindow (or while the timer is running). The wireless device may fail todecode the one or more PDSCHs, e.g., until the end of the window or thetimer expires. In this case, the wireless device may determine aretransmission of MsgA, e.g., after or in response to failing to decodethe one or more PDSCHs and/or an expiry of the timer (or a time reachingthe end of the window).

At the base station, the base station may determine a transmission of asecond PDSCH based on whether the base station receives the PUCCH (e.g.,ACK or NACK) or not. The base station may start a base station timer (ora base station window), e.g., after or in response to receiving MsgA(and/or Transport block 1342) from the wireless device. For example, thebase station transmits, to the wireless device via the PDCCH, a DCIcomprising a downlink assignment. The downlink assignment may compriseone or more fields indicating a time and/or frequency resourceassignment of a PDSCH. The wireless device may receive the PDSCH basedon the downlink assignment. The downlink assignment may further comprisea resource indicator of the PUCCH for ACK/NACK transmission of areception of the PDSCH, a transmit power control command of the PUCCHfor the ACK/NACK transmission, PDSCH-to-HARQ feedback (e.g., theACK/NACK transmission) timing indicator. The base station may determinethat the base station may receive, via the PUCCH indicated by theresource indicator, ACK (e.g., UCI indicating ACK) from the wirelessdevice, e.g., if the wireless device decodes the PDSCH successfully. Thebase station may determine that the base station does not receive(and/or wireless device does not transmit), via the PUCCH indicated bythe resource indicator, ACK (e.g., UCI indicating ACK) from the wirelessdevice, e.g., if the wireless device fails to decode the PDSCH. The basestation may determine a transmission of the second PDSCH (and/or thesecond PDCCH scheduling the second PDSCH), e.g., after or in response toa determination that the base station does not receive (and/or wirelessdevice does not transmit), via the PUCCH indicated by the resourceindicator, ACK (e.g., UCI indicating ACK) from the wireless device. Thebase station may transmit the second PDSCH (and/or the second PDCCHscheduling the second PDSCH), e.g., if the base station timer is running(or during the base station window). The base station may determine notto transmit the second PDSCH (and/or the second PDCCH scheduling thesecond PDSCH), e.g., if the base station timer expires (or after the endof the base station window).

FIG. 27A and FIG. 27B are example diagrams of receiving one or morePDSCHs as per an aspect of an example embodiment of the presentdisclosure. In FIG. 27A, the wireless device initiates a two-step RAprocedure. The wireless device may transmit Preamble 1341 and Transportblock 1342 as a transmission of MsgA 1331. The transport block 1342 maycomprise C-RNTI (e.g., C-RNTI MAC CE indicating the C-RNTI) of thewireless device. The wireless device may start a window (e.g., MsgB RARwindow) or a timer, in response to transmitting the MsgA 1331 (e.g.,transmitting the transport block 1342). The wireless device may monitora downlink control channel during the window (or while the timer isrunning). The wireless device may receive, via the downlink controlchannel, a first PDCCH addressed to the C-RNTI. The wireless device mayfail to decode a first PDSCH scheduled by a first downlink assignmentindicated by a first DCI in the first PDCCH. The wireless device maycontinue to monitor the downlink control channel, e.g., if a (current)time does reach the end of the window or if the timer is running. Thewireless device may receive, via the downlink control channel, a secondPDCCH addressed to the C-RNTI. The wireless device may fail to decode asecond PDSCH scheduled by a second downlink assignment indicated by asecond DCI in the second PDCCH. The wireless device may repeat thisprocess N+1 times (e.g., N+1 attempts to receive N+1 PDSCHs, where N≥1)during the window or while the timer is running, e.g., if the previous Nattempts to receive (and/or decode) N PDSCHs has been failed. Thewireless device may decode N+1-th PDSCH (e.g., MsgB, a response of MsgA)successfully. The wireless device may transmit, via a PUCCH, ACK (e.g.,UCI) based on a downlink assignment indicated by a DCI of PDCCHscheduling the N+1-th PDSCH. There may be a case that the wirelessdevice fails to decode the one or more PDSCHs during the window (oruntil the timer expires). FIG. 27B is an example showing that thewireless device fails to decode N PDSCHs. The wireless device maydetermine a retransmission of MsgA, e.g., after or in response to one ormore PDSCHs received (based on one or more PDCCHs addressed to C-RNTI)and a failure of decoding the one or more PDSCHs during the window (oruntil the timer expires).

In FIG. 27A and/or FIG. 27B, the wireless device may employ an HARQ todecode a PDSCH (MsgB). For example, the first downlink assignment of thefirst DCI in the first PDCCH scheduling the first PDSCH may indicate atleast one of a redundant version of transport block (the PDSCH). Thewireless device may receive the second PDCCH scheduling the secondPDSCH. The second PDCCH may indicate a second redundant version oftransport block (the PDSCH). The wireless device may combine the firstPDSCH and the second PDSCH using a soft combining based on the firstredundant version and the second redundant version. A HARQ processnumber of this PDSCH combining may be predefined or semi-staticallyconfigured (via SIB or RRC). The wireless device may identify a field ofthe (first, second, . . . ) PDCCH indicating the HARQ process number. Anew data indicator (NDI) may be employed for the wireless device todetermine whether the wireless device flush the HARQ buffer of the HARQprocess. For example, the wireless device combine one or more PDSCHsusing the soft combining, e.g., if the HARQ process numberscorresponding to the one or more PDSCHs are the same and/or NDI has notbeen toggled. For example, an NDI indicated by N-th PDCCH is toggled,the wireless device may flush the HARQ buffer corresponding to the HARQprocess number predefined, semi-statically configured, or indicated byN-th PDCCH. For example, an NDI indicated by N-th PDCCH is not toggled,the wireless device may attempt soft combining the received signal(e.g., transport block(s)) in the HARQ buffer with N-th PDSCH scheduledby the N-th PDCCH.

FIG. 28A and FIG. 28B are example diagrams of transmitting one or morePDSCH as per an aspect of an example embodiment of the presentdisclosure. In FIG. 28A, the base station may receive, from a wirelessdevice, Preamble 1341 and Transport block 1342 as a transmission of MsgA1331. The transport block 1342 may comprise C-RNTI (e.g., C-RNTI MAC CEindicating the C-RNTI) of the wireless device. The base station maydetermine, based on a reception timing and or a transmitting timing ofMsgA (or Preamble 1341 and/or Transport block 1342) when the wirelessdevice starts a window (e.g., MsgB RAR window) or a timer, in responseto transmitting the MsgA 1331 (e.g., transmitting the transport block1342). The base station may transmit, to the wireless device via adownlink control channel, a first PDCCH scheduling a first PDSCH (e.g.,MsgB) for the wireless device during the window (or while the timer isrunning). The first PDCCH may be addressed to (or scrambled with) theC-RNTI. The first PDCCH may further schedule a PUCCH based on which thewireless device transmit ACK or NACK of a reception of the first PDSCH.The base station may determine that the reception (decoding) of PDSCH issuccessful, e.g., if the base station receives, from the wireless devicevia the PUCCH, an ACK. The base station may determine that the reception(decoding) of PDSCH is unsuccessful, e.g., if the base station does notreceive, from the wireless device via the PUCCH, an ACK. The basestation may transmit, to the wireless device via the downlink controlchannel, a second PDCCH scheduling a second PDSCH (e.g., MsgB) for thewireless device during the window (or while the timer is running). Thesecond PDCCH may be addressed to (or scrambled with) the C-RNTI. Thesecond PDCCH may indicate a downlink assignment of a second PDSCH. Thebase station may repeat this process during the window (or until thetimer expires), e.g., if no PUCCH corresponding a PDSCH (MsgB) has notbeen received. For example, the base station may repeat this process N+1times (e.g., N+1 attempts to receive N+1 PUCCHs (e.g., ACKs)corresponding to N+1 PDSCHs, where N≥1) during the window or while thetimer is running, e.g., if the previous N PUCCHs indicating a successfulreception (and/or decoding) of previous N PDSCHs has been received.There may be a case that the base station receive, from the wirelessdevice, no PUCCH corresponding to one or more PDSCHs transmitted to thewireless device during the window (or until the timer expires). FIG. 28Bis an example showing that the base station receives no PUCCHcorresponding to N PDSCHs. The base station may determine to stoptransmitting another PDSCH (e.g., MsgB, a response of), e.g., after orin response to no PUCCH corresponding to N PDSCHs (MsgB) received duringthe window (or until the timer expires).

In an example, a wireless device, that detects a PDCCH addressed C-RNTIand fails to decode PDSCH received based on a downlink assignmentindicated by the PDCCH, may continue to monitor (or keep monitoring) thedownlink control channel based on an adjusted timer or window (e.g.,MsgB RAR window). The wireless device may transmit, to a base station,MsgA (e.g., Transport block 1342) and start a timer or a window (e.g.,MsgB RAR window), e.g., after or in response to transmitting the MsgA(e.g., Transport block 1342). The wireless device may receive a PDCCHaddressed to C-RNTI that the wireless device transmits to the basestation via the MsgA and/or Transport block 1342 of the MsgA (e.g.,C-RNTI MAC CE). The wireless device may attempt to receive and/or decodea PDSCH scheduled by the PDCCH. For example, the wireless devicedetermines whether the PDSCH is successfully decoded or not base on acyclic redundancy check (CRC) result (decoding success or failure) forthe PDSCH. For example, the wireless device continues to monitor (orkeeps monitoring) the downlink control channel, e.g., by adjusting (orextending) the timer or the window (MsgB RAR window). Adjusting (orextending) the timer or the window (msgB RAR window may be implementedone or more ways. For example, the wireless device restarted the timeror the window, e.g., after or in response to a determination that thePDSCH decoding is failed (e.g., based on the CRC result). The wirelessdevice may restart the timer or the window, e.g., after or in responseto a determination that the PDSCH decoding is failed (e.g., based on theCRC result). The wireless device may determine a restarting timing ofthe timer or the window based on (e.g., with respect to, depending on,or in response to) a reception timing of the PDCCH or a reception timingof the PDSCH scheduled by the PDCCH. The wireless device may start asecond timer or a second window, e.g., after or in response to adetermination that the PDSCH decoding is failed (e.g., based on the CRCresult). For example, the second timer and the second timer may have thesame timer value predefined or semi-statically configured by SIB or RRCmessage(s). For example, the second timer and the second timer may havethe different timer values predefined or semi-statically configured bySIB or RRC message(s). The wireless device may determine a startingtiming of the second timer or the second window based on (e.g., withrespect to, depending on, or in response to) a reception timing of thePDCCH or a reception timing of the PDSCH scheduled by the PDCCH. Duringthe adjusted timer or window (by restating the timer or the window orstarting the second timer or the second window), the wireless device maymonitor the downlink control channel for a second PDSCH (MsgB).

FIG. 29 is an example of adjusted (or extended) window (e.g., MsgB RARwindow) as per an aspect of an example embodiment of the presentdisclosure. The wireless device initiating a two-step RA procedure maytransmit MsgA. Transport block of the MsgA may comprise C-RNTI (e.g.,C-RNTI MAC CE) of the wireless device. The wireless device may start atimer or a window (e.g., MsgB RAR window), e.g., in response totransmitting the MsgA (or Transport block). The wireless device maymonitor a downlink control channel for a response (e.g., MsgB) of theMsgA during the window (or while the timer is running). The wirelessdevice may receive a first PDCCH addressed to C-RNTI during the window(or while the timer is running). The first PDCCH may comprise a firstdownlink assignment indicating scheduling information (e.g.,time/frequency radio resource) of a first PDSCH (e.g., MAC PDUcomprising the MsgB). The wireless device may receive the first PDSCHand attempt to decode the first PDSCH. The wireless device may determinea failure of decoding the first PDSCH, e.g., based on a CRC result(e.g., indicating a decoding failure) for the first PDSCH. The wirelessdevice may attempt to receive a second PDCCH and/or a second PDSCHscheduled by the second PDCCH. For example, the wireless device mayadjust (or extend) the timer or the window. The adjusted (extended)timer or the window may enable for the base station to flexibly allocatedownlink resource(s) of downlink transmission(s) in a network. Thewireless device may receive, during the adjusted (or extended) timer orwindow, the second PDCCH that schedules the second PDSCH (e.g., MsgB).

FIG. 30 is an example of adjusted (or extended) window as per an aspectof an example embodiment of the present disclosure. The adjusted timeror window may be implemented in one or more ways. For example, theadjusted timer or window may be implemented based on restarting thetimer or window. For example, as shown in FIG. 29 , the wireless devicestarts MsgB RAR window, e.g., after or in response to transmitting theMsgA (or Transport block). The wireless device may determine that adecoding failure of a first PDSCH (e.g., as described/shown in FIG. 29). The wireless device may determine to adjust or extend the MsgB RARwindow by restarting the MsgB RAR window, as shown in Example 1 of FIG.30 , after or in response to a determination of the decoding failure.The restart timing of the MsgB RAR window may be determined based on anoffset (predefined or semi-statically configured) and/or a receptiontiming (e.g., at the end of PDCCH reception or coreset of the firstPDCCH) of a first PDCCH. The restart timing of the MsgB RAR window maybe determined based on an offset (predefined or semi-staticallyconfigured) and/or a reception timing of a first PDSCH. For example, theadjusted timer or window may be implemented based on starting a secondtimer or a second window. For example, the wireless device starts afirst MsgB RAR window, e.g., after or in response to transmitting theMsgA (or Transport block). The wireless device may determine that adecoding failure of a first PDSCH (e.g., as described/shown in FIG. 29). The wireless device may determine to adjust or extend the MsgB RARwindow by starting a second MsgB RAR window, as shown in Example 2 ofFIG. 30 , after or in response to a determination of the decodingfailure. The start timing of the second MsgB RAR window may bedetermined based on an offset (predefined or semi-statically configured)and/or a reception timing (e.g., at the end of PDCCH reception orcoreset of the first PDCCH) of a first PDCCH. The start timing of thesecond MsgB RAR window may be determined based on an offset (predefinedor semi-statically configured) and/or a reception timing of a firstPDSCH.

A number of adjustments of MsgB RAR window in FIG. 30 may be limited toone. For example, if the wireless device does not decode at least onePDSCH (MsgB) during a adjusted (extended) timer or a window (e.g.,implemented by any example in FIG. 30 ), the wireless device maydetermine a retransmission of MsgA.

The wireless device may adjust a MsgB RAR window in FIG. 30 for each ofN decoding failures in FIG. 27A or FIG. 27B. For example, the wirelessdevice may adjust (or extend), e.g., based on one of examples in FIG. 30, the MsgB RAR window, after or in response to a failure of decodingn-th PDSCH (msgB), where 1≤n≤N. For example, the wireless device mayadjust (or extend), e.g., based on one of examples in FIG. 30 , the MsgBRAR window, after or in response to a failure of decoding n+1-th PDSCH(msgB), where 1≤n+1 N, and so on. For example, there may be a firstvalue limiting a number of adjustments of the MsgB RAR window. The firstvalue may be predefined or indicated by parameter(s) in SIB or RRC. Thefirst value may indicate a number of PDSCH (MsgB) (re)transmission fromthe base station. The first value may be the same to a size of redundantversion pattern predefined or semi-statically configured for the PDSCH(MsgB) transmission, e.g., if HARQ for the PDSCH (MsgB) is supported.The wireless device may determine a retransmission of MsgA, e.g., if thenumber of adjustment (or a number of PDSCH (MsgB) (re)transmissions)reaches the first value.

For example, a wireless device may transmit a message comprising apreamble and a transport block comprising a wireless device identifier.The wireless device may receive, via a downlink control channel, a firstdownlink control information using the wireless device identifier. Thewireless device may determine a decoding failure of a response receivedbased on the first downlink control information. In response to thedecoding failure, the wireless device may adjust a time interval tomonitor the downlink control channel. The wireless device may receivinga retransmission of the response during the adjusted time interval. Thewireless device may transmit an uplink control signal in response to adecoding success of the response. For example, a transmission timing ofthe uplink control signal is determined based on a timing advance valueindicated by the response. For example, the adjusted time intervalstarts in response to receiving the first response. For example, theadjusted time interval starts in response to receiving the downlinkcontrol information. For example, the wireless device may start a firstmonitoring window in response to transmitting the transport block. Forexample, the time interval comprises a first duration of the firstmonitoring window that restarts in response to receiving the firstresponse. For example, the time interval comprises a first duration ofthe first monitoring window that restarts in response to receiving thedownlink control information. For example, the time interval comprises asecond duration of a second monitoring window that starts in response toreceiving the response. For example, the time interval comprises asecond duration of a second monitoring window that starts in response toreceiving the downlink control information. For example, the wirelessdevice identifier is a cell radio network temporary identifier (C-RNTI).For example, the wireless device has not been received a timing advancevalue. For example, a time alignment timer of the wireless deviceexpires. For example, the second response indicates a timing advancevalue. For example, the wireless device may adjust an uplinktransmission timing for the uplink control signal based on the timingadvance value. For example, the wireless device transmits the messagecomprising the preamble and the transport block in response toinitiating a two-step random access procedure. For example, the wirelessdevice may, e.g., in response to transmitting the transport block,monitor the downlink control channel using the wireless deviceidentifier and a second identifier. For example, the wireless devicemay, e.g., in response to the decoding failure, monitor the downlinkcontrol channel using the wireless device identifier.

For example, a wireless device may transmit a first message comprising afirst preamble and a first transport block comprising a wireless deviceidentifier. The wireless device may receive, via downlink controlchannel, a first downlink control information using the wireless deviceidentifier. The wireless device may determine a decoding failure of afirst response received based on the first downlink control information.The wireless device may adjust a time interval to monitor the downlinkcontrol channel in response to determining the failure. The wirelessdevice may determine that no response received during the adjusted timeinterval. The wireless device may transmit a second message comprising asecond preamble and a second transport block in response to thedetermining.

What is claimed is:
 1. A method comprising: transmitting, by a wirelessdevice, a first preamble via a cell; receiving a downlink grant for arandom access response; determining a failure to receive the randomaccess response; determining, based on the failure and a time alignmenttimer of the cell, an uplink signal for transmission via the cell,wherein the uplink signal is either a second preamble or a negativeacknowledgement; and transmitting the uplink signal, wherein the uplinksignal is the second preamble in response to the time alignment timer,associated with the cell, not being running, and the uplink signal isthe negative acknowledgement in response to the time alignment timerbeing running.
 2. The method of claim 1, further comprising determininga timing advance value is invalid in response to the time alignmenttimer not being running, and wherein the uplink signal being the secondpreamble is based on determining that the timing advance value isinvalid.
 3. The method of claim 1, further comprising determining atiming advance value is valid in response to the time alignment timerbeing running, and wherein the uplink signal being the negativeacknowledgement is based on determining that the timing advance value isvalid.
 4. The method of claim 1, wherein transmitting the first preamblecomprises transmitting a first message comprising the first preamble anda first transport block.
 5. The method of claim 4, wherein the firsttransport block comprises a cell radio network temporary identifier(C-RNTI) of the wireless device.
 6. The method of claim 5, whereinreceiving the downlink grant comprises receiving, based on the C-RNTI, adownlink control information comprising the downlink grant.
 7. Themethod of claim 1, wherein the determining based on the failure is basedon failing to decode the random access response.
 8. The method of claim1, wherein the uplink signal comprising the second preamble is based ona two-step random access procedure.
 9. A wireless device comprising: oneor more processors; and memory storing instructions that, when executedby the one or more processors, cause the wireless device to: transmit afirst preamble via a cell; receive a downlink grant for a random accessresponse; determine a failure to receive the random access response;determine, based on the failure and a time alignment timer of the cell,an uplink signal for transmission via the cell, wherein the uplinksignal is either a second preamble or a negative acknowledgement; andtransmit the uplink signal, wherein the uplink signal is the secondpreamble in response to the time alignment timer, associated with thecell, not being running, and the uplink signal is the negativeacknowledgement in response to the time alignment timer being running.10. The wireless device of claim 9, wherein the instructions furthercause the wireless device to determine a timing advance value is invalidin response to the time alignment timer not being running, and whereinthe uplink signal being the second preamble is based on determining thatthe timing advance value is invalid.
 11. The wireless device of claim 9,wherein the instructions further cause the wireless device to determinea timing advance value is valid in response to the time alignment timerbeing running, and wherein the uplink signal being the negativeacknowledgement is based on determining that the timing advance value isvalid.
 12. The wireless device of claim 9, wherein to transmit the firstpreamble, the instructions further cause the wireless device to transmita first message comprising the first preamble and a first transportblock.
 13. The wireless device of claim 12, wherein the first transportblock comprises a cell radio network temporary identifier (C-RNTI) ofthe wireless device.
 14. The wireless device of claim 13, wherein toreceive the downlink grant, the instructions further cause the wirelessdevice to receive, based on the C-RNTI, downlink control informationcomprising the downlink grant.
 15. The wireless device of claim 9,wherein to determine based on the failure, the instructions furthercause the wireless device to determine based on failing to decode therandom access response.
 16. A system comprising: a base stationcomprising: one or more first processors and first memory storing firstinstructions that, when executed by one or more first processors, causethe base station to: receive a first preamble via a cell; and transmit adownlink grant for a random access response; and a wireless devicecomprising: one or more second processors; and second memory storingsecond instructions that, when executed by the one or more secondprocessors, cause the wireless device to: transmit, to the base station,the first preamble via the cell; receive, from the base station, thedownlink grant for the random access response; determine a failure toreceive the random access response; determine, based on the failure anda time alignment timer of the cell, an uplink signal for transmissionvia the cell, wherein the uplink signal is either a second preamble or anegative acknowledgement; and transmit the uplink signal to the basestation, wherein the uplink signal is the second preamble in response tothe time alignment timer, associated with the cell, not being running,and the uplink signal is the negative acknowledgement in response to thetime alignment timer being running.